bluuebunny/crossref_metadata_2025 huggingface dataset:
The Cycling Physiology of Miguel Indurain 14 Years After Retirement
Authors: Mujika Iñigo
Published: August 2016

Age-related fitness declines in athletes can be due to both aging and detraining. Very little is known about the physiological and performance decline of professional cyclists after retirement from competition. To gain some insight into the aging and detraining process of elite cyclists, 5-time Tour de France winner and Olympic Champion Miguel Indurain performed a progressive cycle-ergometer test to exhaustion 14 y after retirement from professional cycling (age 46 y, body mass 92.2 kg). His maximal values were oxygen uptake 5.29 L/min (57.4 mL · kg−1 · min−1), aerobic power output 450 W (4.88 W/kg), heart rate 191 beats/min, blood lactate 11.2 mM. Values at the individual lactate threshold (ILT): 4.28 L/min (46.4 mL · kg−1 · min−1), 329 W (3.57 W/kg), 159 beats/min, 2.4 mM. Values at the 4-mM onset of blood lactate accumulation (OBLA): 4.68 L/min (50.8 mL · kg−1 · min−1), 369 W (4.00 W/kg), 170 beats/min. Average cycling gross efficiency between 100 and 350 W was 20.1%, with a peak value of 22.3% at 350 W. Delta efficiency was 27.04%. Absolute maximal oxygen uptake and aerobic power output declined by 12.4% and 15.2% per decade, whereas power output at ILT and OBLA declined by 19.8% and 19.2%. Larger declines in maximal and submaximal values relative to body mass (19.4–26.1%) indicate that body composition changed more than aerobic characteristics. Nevertheless, Indurain’s absolute maximal and submaximal oxygen uptake and power output still compare favorably with those exhibited by active professional cyclists.
Evaluation of Change-of-Direction Movements in Young Rugby Players
Authors: Condello Giancarlo , Minganti Carlo , Lupo Corrado , Benvenuti Cinzia , Pacini Daniele , Tessitore Antonio
Published: August 2016

The evaluation of change-of-direction (COD) performance is strongly focused on the time spent to perform the test trials, while much less is known about the technical execution adopted during the COD movements. Thus, the purposes of this study were to evaluate (1) the relationship between straight- and COD-sprint tests and (2) the technical execution of COD movements in relation to different age categories of young rugby players. Young rugby players (N = 157, age range 8–19 y) completed a test battery composed of a 15-m straight-sprint test (15SS) and a 15-m sprint test performed with 2 changes of direction (15COD). Significant differences were detected between age categories for both tests. Significant correlations were found between 15SS and 15COD. The analysis of the technical execution of the 15COD test showed differences between age categories, with a prevalence of rounded turns up to the U15 category. These findings confirmed the relationship between straight and COD abilities in young male rugby players. Moreover, the new approach introduced by this study, based on the analysis of COD technical execution, revealed that this performance could be conditioned by the age and mastery level of the players.
Cardiorespiratory Responses to the 30-15 Intermittent Ice Test
Authors: Besson Cyril , Buchheit Martin , Praz Manu , Dériaz Olivier , Millet Grégoire P.
Published: August 2016

Purpose:

In this study, the authors compared the cardiorespiratory responses between the 30–15 Intermittent Ice Test (30-15IIT) and the 30–15 Intermittent Fitness Test (30-15IFT) in semiprofessional hockey players.

Methods:

Ten players (age 24 ± 6 y) from a Swiss League B team performed the 30-15IIT and 30-15IFT in random order (13 ± 4 d between trials). Cardiorespiratory variables were measured with a portable gas analyzer. Ventilatory threshold (VT), respiratory-compensation point (RCP), and maximal speeds were measured for both tests. Peak blood lactate ([Lapeak]) was measured at 1 min postexercise.

Results:

Compared with 30-15IFT, 30-15IIT peak heart rate (HRpeak; mean ± SD 185 ± 7 vs 189 ± 10 beats/min, P = .02) and peak oxygen consumption (VO2peak; 60 ± 7 vs 62.7 ± 4 mL/min/kg, P = .02) were lower, whereas [Lapeak] was higher (10.9 ± 1 vs 8.6 ± 2 mmol/L, P < .01) for the 30–15IIT. VT and RCP values during the 30-15IIT and 30-15IFT were similar for %HRpeak (76.3% ± 5% vs 75.5% ± 3%, P = .53, and 90.6% ± 3% vs. 89.8% ± 3%, P = .45) and % VO2peak (62.3% ± 5% vs 64.2% ± 6%, P = .46, and 85.9% ± 5% vs 84.0% ± 7%, P = .33). VO2peak (r = .93, P < .001), HRpeak (r = .86, P = .001), and final velocities (r = .69, P = .029) were all largely to almost perfectly correlated.

Conclusions:

Despite slightly lower maximal cardiorespiratory responses than in the field-running version of the test, the on-ice 30-15IIT is of practical interest since it is a specific maximal test with a higher anaerobic component.
Enhanced Performance With Elastic Resistance During the Eccentric Phase of a Countermovement Jump
Authors: Aboodarda Saied Jalal , Yusof Ashril , Osman N.A. Abu , Thompson Martin W. , Mokhtar A. Halim
Published: August 2016

Purpose:

To identify the effect of additional elastic force on the kinetic and kinematic characteristics, as well as the magnitude of leg stiffness, during the performance of accentuated countermovement jumps (CMJs).

Methods:

Fifteen trained male subjects performed 3 types of CMJ including free CMJ (FCMJ; ie, body weight), ACMJ-20, and ACMJ-30 (ie, accentuated eccentric CMJ with downward tensile force equivalent to 20% and 30% body mass, respectively). A force platform synchronized with 6 high-speed infrared cameras was used to measure vertical ground-reaction force (VGRF) and displacement.

Results:

Using downward tensile force during the lowering phase of a CMJ and releasing the bands at the start of the concentric phase increased maximal concentric VGRF (6.34%), power output (23.21%), net impulse (16.65%), and jump height (9.52%) in ACMJ-30 compared with FCMJ (all P < .05). However, no significant difference was observed in the magnitude of leg stiffness between the 3 modes of jump. The results indicate that using downward recoil force of the elastic material during the eccentric phase of a CMJ could be an effective method to enhance jump performance by applying a greater eccentric loading on the parallel and series elastic components coupled with the release of stored elastic energy.

Conclusions:

The importance of this finding is related to the proposition that power output, net impulse, takeoff velocity, and jump height are the key parameters for successful athletic performance, and any training method that improves impulse and power production may improve sports performance, particularly in jumping aspects of sport.
Anthropometric and Physiological Characteristics in Young Afro-Caribbean Swimmers: A Preliminary Study
Authors: Hue Olivier , Antoine-Jonville Sophie , Galy Olivier , Blonc Stephen
Published: August 2016

The authors investigated the anthropometric and physiological characteristics of young Guadeloupian competitive swimmers in relation to swimming performance and compared the abilities of these children with those of the young white swimmers reported in the literature. All 2004 competitive swimmers between 10 and 14 y old (126 children, 61 boys and 65 girls, 12.0 ± 1.3 y) from Guadeloupe underwent anthropometric measurements and physiological and performance testing. Six boys on the French national swimming team are referred to hereafter as the 2011 elite subgroup. Anthropometric parameters, a jump-and-reach test, glide, and estimated aerobic power (eVO2max) were assessed in terms of swimming-performance analysis through a 400-m test. This study demonstrated that the Guadeloupian swimmers had more body fat than most age-matched white swimmers but had very poor hydrostatic lift; they had higher peak jump height and they swam as well as their white counterparts. The variability in 400-m performance between subjects was best described by glide, age, and eVO2max. Compared with the group of boys with the same age, the 2011 elite subgroup was significantly better for arm span, peak jump height, glide, and 400-m and 15-m performances. Further research is needed to investigate motor organization and energy cost of swimming in Afro-Caribbean swimmers.
Heart-Rate Responses by Playing Position During Ball Drills in Basketball
Authors: Delextrat Anne , Kraiem Semah
Published: August 2016

The physiological load experienced during basketball drills is crucial to understand players’ adaptation to team-sport training and plan physical-conditioning programs.

Purpose:

To compare mean heart-rate (HRmean) responses by playing position during 2-a-side (2v2) and 3-a-side (3v3) ball drills in male junior basketball players and explore the relationship between HRmean and repeated-sprint ability (RSA).

Methods:

Thirtyone players volunteered to participate in this study. On separate occasions, they performed 2v2 and 3v3 ball drills and 6 repetitions of shuttle-run sprints of 20 m (10+10 m), departing every 20 s (RSA). Ball drills took place on the full length but only half the width of the court and were three 4-min bouts separated by 1-min rest periods. An analysis of variance (ANOVA) assessed the effect of the number of players on court (2v2 vs 3v3) and playing position (guards vs forwards vs centers) on HRmean, and a Pearson correlation coefficient evaluated the relation between HRmean and RSA.

Results:

The main results showed greater HRmean in 2v2 than in 3v3 ball drills (P < .001) in all playing positions (90.7% ± 1.3% vs 87.6% ± 3% of HRpeak in guards, 91.3% ± 2.1% vs 87.5% ± 3.7% of HRpeak for forwards, and 88.2% ± 3.5% vs 82.2% ± 5.6% of HRpeak in centers, respectively, for 2v2 and 3v3). In addition, centers were characterized by lower HRmean than guards and forwards in 3v3 only (P = .018).

Conclusions:

These results suggest that 2v2 drills should be preferred to 3v3 drills for aerobic conditioning, in particular for centers. Finally, RSA does not seem to influence players’ acute responses to ball drills.
Development of a Comprehensive Performance-Testing Protocol for Competitive Surfers
Authors: Sheppard Jeremy M. , Nimphius Sophia , Haff Greg G. , Tran Tai T. , Spiteri Tania , Brooks Hedda , Slater Gary , Newton Robert U.
Published: August 2016

Purpose:

Appropriate and valid testing protocols for evaluating the physical performances of surfing athletes are not well refined. The purpose of this project was to develop, refine, and evaluate a testing protocol for use with elite surfers, including measures of anthropometry, strength and power, and endurance.

Methods:

After pilot testing and consultation with athletes, coaches, and sport scientists, a specific suite of tests was developed. Forty-four competitive junior surfers (16.2 ± 1.3 y, 166.3 ± 7.3 cm, 57.9 ± 8.5 kg) participated in this study involving a within-day repeated-measures analysis, using an elite junior group of 22 international competitors (EJG), to establish reliability of the measures. To reflect validity of the testing measures, a comparison of performance results was then undertaken between the EJG and an age-matched competitive junior group of 22 nationally competitive surfers (CJG).

Results:

Percent typical error of measurement (%TEM) for primary variables gained from the assessments ranged from 1.1% to 3.0%, with intraclass correlation coefficients ranging from .96 to .99. One-way analysis of variance revealed that the EJG had lower skinfolds (P = .005, d = 0.9) than the CJG, despite no difference in stature (P = .102) or body mass (P = .827). The EJG were faster in 15-m sprint-paddle velocity (P < .001, d = 1.3) and had higher lower-body isometric peak force (P = .04, d = 0.7) and superior endurance-paddling velocity (P = .008, d = 0.9).

Conclusions:

The relatively low %TEM of these tests in this population allows for high sensitivity to detect change. The results of this study suggest that competitively superior junior surfers are leaner and possess superior strength, paddling power, and paddling endurance.
Cycling Attributes That Enhance Running Performance After the Cycle Section in Triathlon
Authors: Etxebarria Naroa , Anson Judith M. , Pyne David B. , Ferguson Richard A.
Published: August 2016

Purpose:

To determine how cycling with a variable (triathlon-specific) power distribution affects subsequent running performance and quantify relationships between an individual cycling power profile and running ability after cycling.

Methods:

Twelve well-trained male triathletes (VO2peak 4.9 ± 0.5 L/min; mass 73.5 ± 7.7 kg; mean ± SD) undertook a cycle VO2peak and maximal aerobic power (MAP) test and a power profile involving 6 maximal efforts (6 s to 10 min). Each subject then performed 2 experimental 1-h cycle trials, both at a mean power of 65% MAP, at either variable power (VAR) ranging from 40% to 140% MAP or constant power (CON) followed by an outdoor 9.3-km time-trial run. Subjects also completed a control 9.3-km run with no preceding exercise.

Results:

The 9.3-km run time was 42 ± 37 s slower (mean ± 90% confidence limits [CL]) after VAR (35:32 ± 3:18 min:s, mean ± SD) compared with CON cycling (34:50 ± 2:49 min:s). This decrement after VAR appeared primarily in the first half of the run (35 ± 20 s; mean ± 90% CL). Higher blood lactate and rating of perceived exertion after 1 h VAR cycling were moderately correlated (r = .51–.55; ± ~.40) with a larger decrement in run performance. There were no clear associations between the power-profile test and decrement in run time after VAR compared with CON.

Conclusions:

A highly variable power distribution in cycling is likely to impair 10-km triathlon run performance. Training to lower physiological and perceptual responses during cycling should limit the negative effects on triathlon running.
Training and Competition Workloads and Fatigue Responses of Elite Junior Cricket Players
Authors: McNamara Dean J. , Gabbett Tim J. , Naughton Geraldine , Farhart Patrick , Chapman Paul
Published: August 2016

Purpose:

This study investigated key fatigue and workload variables of cricket fast bowlers and nonfast bowlers during a 7-wk physical-preparation period and 10-d intensified competition period.

Methods:

Twenty-six elite junior cricketers (mean ± SD age 17.7 ± 1.1 y) were classified as fast bowlers (n = 9) or nonfast bowlers (n = 17). Individual workloads were measured via global positioning system technology, and neuromuscular function (countermovement jump [relative power and flight time]), endocrine (salivary testosterone and cortisol concentrations), and perceptual well-being (soreness, mood, stress, sleep quality, and fatigue) markers were recorded.

Results:

Fast bowlers performed greater competition total distance (median [interquartile range] 7049 [3962] m vs 5062 [3694] m), including greater distances at low and high speeds, and more accelerations (40 [32] vs 19 [21]) and had a higher player load (912 [481] arbitrary units vs 697 [424] arbitrary units) than nonfast bowlers. Cortisol concentrations were higher in the physical-preparation (mean ± 90% confidence intervals, % likelihood; d = –0.88 ± 0.39, 100%) and competition phases (d = –0.39 ± 0.30, 85%), and testosterone concentrations, lower (d = 0.56 ± 0.29, 98%), in the competition phase in fast bowlers. Perceptual well-being was poorer in nonfast bowlers during competition only (d = 0.36 ± 0.22, 88%). Differences in neuromuscular function between groups were unclear during physical preparation and competition.

Conclusions:

These findings demonstrate differences in the physical demands of cricket fast bowlers and nonfast bowlers and suggest that these external workloads differentially affect the neuromuscular, endocrine, and perceptual fatigue responses of these players.
Time-on-Pitch or Full-Game GPS Analysis Procedures for Elite Field Hockey?
Authors: White Andrew D. , MacFarlane Niall
Published: August 2016

Purpose:

The current study assessed the impact of full-game (FG) and time-on-pitch (TOP) procedures for global-positioning-system (GPS) analysis on the commonly used markers of physical performance in elite field hockey.

Methods:

Sixteen international male field hockey players, age 19–30, were studied (yielding 73 player analyses over 8 games). Physical activity was recorded using a 5-Hz GPS.

Results:

Distance covered, player load, maximum velocity, high-acceleration efforts, and distance covered at specified speed zones were all agreeable for both analysis procedures (P > .05). However, percentage time spent in 0–6 km/h was higher for FG (ES: –21% to –16%; P < .001), whereas the percentage time in all other speed zones (1.67–3.06 m/s, 3.06–4.17 m/s, 4.17–5.28 m/s, and > 6.39 m/s) and relative distance (m/min) were higher for TOP (ES: 8–10%, 2–7%, 2–3%, 1–1%, 0–1%, respectively; P < .001).

Conclusions:

These data demonstrate that GPS analysis procedures should be appropriate for the nature of the sport being studied. In field hockey, TOP and FG analysis procedures are comparable for distance-related variables but significantly different for time-dependent factors. Using inappropriate analysis procedures can alter the perceived physiological demand of elite field hockey because of “rolling” substitutions. Inaccurate perception of physiological demand could negatively influence training prescription (for both intensity and volume).
Evaluating Training Adaptation With Heart-Rate Measures: A Methodological Comparison
Authors: Plews Daniel J. , Laursen Paul B. , Kilding Andrew E. , Buchheit Martin
Published: August 2016

The aim of this study was to compare 2 different methodological assessments when analyzing the relationship between performance and heart-rate (HR) -derived indices (resting HR [RHR] and HR variability [HRV]) to evaluate positive adaptation to training. The relative change in estimated maximum aerobic speed (MAS) and 10-km-running performance was correlated to the relative change in RHR and the natural logarithm of the square root of the mean sum of the squared differences between R-R intervals on an isolated day (RHRday; Ln rMSSDday) or when averaged over 1 wk (RHRweek; Ln rMSSDweek) in 10 runners who responded to a 9-wk training intervention. Moderate and small correlations existed between changes in MAS and 10-km-running performance and RHRday (r = .35, 90%CI [–.35, .76] and r = –.21 [–.68, .39]), compared with large and very large correlations for RHRweek (r = –.62 [–.87, –.11] and r = .73 [.30, .91]). While a trivial correlation was observed for MAS vs Ln rMSSDday (r = –.06 [–.59, .51]), a very large correlation existed with Ln rMSSDweek (r = .72 [.28, .91]). Similarly, changes in 10-km-running performance revealed a small correlation with Ln rMSSDday (r = –.17 [–.66, .42]), vs a very large correlation for Ln rMSSDweek (r = –.76 [–.92, –.36]). In conclusion, the averaging of RHR and HRV values over a 1-wk period appears to be a superior method for evaluating positive adaption to training compared with assessing its value on a single isolated day.
The Effect of Wind on 100-m Sprint Times
Authors: Linthorne Nicholas P.
Published: August 2016

The effect of wind on the race times of international standard 100-m sprinters was determined using statistical information from official competitions. A time adjustment curve derived from mathematical models was fitted to performances by the finalists at the U.S. Olympic Trials and TAC Championships over the last 10 years, and to multiple performances by individual athletes at recent Olympic Games and World Championships. Consistent results were obtained from the two studies. The rate of improvement in. race time gradually decreased with increasing wind velocity, and so the disadvantage of a head wind was greater than the benefit of a tail wind of the same magnitude. The advantage of a 2-m/s following wind was 0.10 ± 0.01 s for the male sprinters and 0.12 ± 0.02 s for the female sprinters. These results indicated that the altitude of Mexico City (2,250 m) provides an advantage of about 0.07 s. Time adjustment versus wind velocity curves are presented that allow comparison of the merit of 100-m sprint times achieved under diverse wind conditions. The curves supersede those derived by previous investigators.
Landing Strategies Used by Gymnasts on Different Surfaces
Authors: McNitt-Gray Jill L , Yokoi Takashi , Millward Carl
Published: August 2016

In this study, landing strategies of gymnasts were hypothesized to change with different landing surfaces. This hypothesis was tested by comparing the kinematics and reaction force-time characteristics of two-foot competition-style drop landings performed by male and female collegiate gymnasts onto three surfaces (soft mat, stiff mat, no mat). Significantly lower peak vertical forces, longer landing phase times, and greater knee and hip flexion were observed between the no mat condition and the mat conditions. Knee flexion and peak knee flexion velocities were also observed to be significantly greater for landings on the stiff mat than those on the soft mat. These results indicate that the gymnasts in this study modulated total body stiffness in response to changes in landing surface conditions by using a multi joint solution. In addition, the presence of a mat may reduce the need for joint flexion and may alter the vertical impulse characteristics experienced during landing.
Approach to a Biomechanical Profile of Dismounts and Release–Regrasp Skills of the High Bar
Authors: Brüggemann Gert-Peter , Cheetham Phillip J. , Alp Yilmaz , Arampatzis Diamantis
Published: August 2016

At the 1992 Barcelona Olympic Games, 70 dismounts and release-regrasp movements on the high bar were selected from films gathered with three synchronized cameras during the compulsory and the optional men's high bar competition. The skills were classified into 10 groups depending on the direction of rotation, body configuration, and flight projection. Kinematic variables were used to profile the movement groups. Statistically significant differences between the groups were identified by ANOVA. Three groups with significant differences in terms of the maximum values and the locations of the maxima could be differentiated. These were (a) backward rotating swings with an increase of rotation (e.g., overgrip giant swing—triple backward tuck somersault dismount), (b) backward rotating swings with a change of the direction of rotation (e.g., overgrip giant—Tkatchov straddle), and (c) forward rotating swings with an increase or a decrease of rotation (e.g., undergrip giant swing—Jaeger somersault).
Kinematic Analysis of Skating Technique of Olympic Skiers in the Women's 30-km Race
Authors: Gregory Robert W. , Humphreys Sean E. , Street Glenn M.
Published: August 2016

The women's 30-km freestyle cross-country race at the 1992 Winter Olympic Games was selected to determine the kinematic differences between more and less successful skiers. Three-dimensional filming techniques were used to capture the movement patterns on level terrain of 8 skiers who placed in the top 50% (Group 1) and 8 skiers who placed in the bottom 50% (Group 2) of the field. The mean cycle velocity for Group 1 was significantly faster (p < .005) than the velocity for Group 2. Significant correlations (p < .05) were found between race velocity and cycle velocity (r = .89) and between cycle length and cycle rate (r = -.82). Group 1 had significantly greater (p < .03) weak-side elbow flexion at pole plant, as well as less (p < .01) weak-side elbow extension and more (p < .05) trunk flexion during poling. The mean cycle velocity differences between Groups 1 and 2 may have been the result of smaller resistive and/or larger propulsive forces.
The Influence of Heel Counter Rigidity on Rearfoot Motion during Running
Authors: Gheluwe Bart Van , Tielemans Rudi , Roosen Philip
Published: August 2016

The purpose of the current study was to examine rearfoot motion using three-dimensional recording techniques and shoes with varying heel counter rigidity. The results showed that only the more rigid shoes tended to create significant differences between calcaneal and shoe heel eversion during ground contact, except close to heel-strike. The rigid shoe thus resisted eversional forces. The calcaneus, however, was not prevented from slipping within the shoe and from everting as much or nearly as fast as in a shoe with a more flexible heel counter. In order to simulate two-dimensional recording techniques commonly used in rearfoot studies, a two-dimensional reduction of the original three-dimensional angular data was performed. However, the results produced were similar if torsional movement between the foot and shoe was ignored.
Double Poling Kinematics and Performance in Cross-Country Skiing
Authors: Smith Gerald A. , Fewster Jon B. , Braudt Steven M.
Published: August 2016

Olympic skiers in the women's 30-km race were analyzed as they double poled on a moderate downhill slope. Movement patterns of 20 skiers were analyzed 10 from a top finishing group and 10 from slower finishers in the bottom third of the field. Skiers in the faster group not only were faster overall in the race but were faster as they double poled through the site (6.75 vs. 6.43 m/s). Cycle length was significantly correlated with cycle velocity (r = .81). Trunk flexion and shoulder extension during poling were similar between groups; however, considerable variability of shoulder positioning was noted for both groups of skiers. Distinct shoulder-elbow-pole positioning differences were noted among skiers. Disadvantageous positionin» of the shoulder at the beginning of poling was related to poorer pole inclination during elbow extension. While many skiers in both fast and slow groups double poled with good positioning, others would benefit from greater shoulder flexion to maximize double poling performance.
Influence of Fulcrum Position on Springboard Response and Takeoff Performance in the Running Approach
Authors: Jones Ian C. , Miller Doris L.
Published: August 2016

The running forward springboard approaches of 20 divers on the U.S. senior national diving team were analyzed using planar video analysis and accelerometer output; the purpose was to investigate kinematic responses of the springboard tip and divers' lower extremities to alterations in fulcrum setting. Divers executed jump takeoffs from a 1-m springboard with the fulcrum at their preferred setting as well as 0.144 m (two fulcrum numbers) forward and 0.144 m back from that location. Potential advantages of setting the fulcrum back further from the tip (as opposed to closer) included greater downward board tip vertical velocity at the beginning of takeoff, more time to generate angular momentum, and increased vertical velocity going into flight. However, setting the fulcrum further back required the diver to achieve longer hurdle flight durations and to reverse downward motion from a more flexed knee position. Accelerometer output in the absence of video was not beneficial as a means of providing immediate performance feedback for coaching purposes.
The Effects of Cycling on Running Mechanics
Authors: Quigley Edward J. , Richards James G.
Published: August 2016

This study investigated the mechanical effects that cycling has on running style which may explain the discomfort associated with the transition from cycling to running. The joint angles, angular velocities, reaction forces, and reaction moments of the left and right hip, knee, and ankle joints as well as stance time, flight time, stride length, and maximum vertical displacement of the center of gravity were measured using high-speed video and ground reaction force data. Data were collected from 11 competitive biathletes and triathletes. Each subject's running mechanics were determined from 10 trials for each of three conditions: (a) unfatigued, (b) immediately following 30 min of running, and (c) immediately following 30 min of bicycling. The results indicate that a person's running mechanics, as described by the variables above, are virtually unchanged between each of the three conditions. Therefore, awkwardness of the bicycle-to-run transition may not be related to a change in running mechanics.
Kinematic Analysis of the Barbell during the Snatch Movement of Elite Asian Weight Lifters
Authors: Isaka Tadao , Okada Junichi , Funato Kazuo
Published: August 2016

The purpose of this study was to describe the kinematic characteristics of the snatch technique from the viewpoint of barbell trajectory. Subjects included 6 elite male Asian weight lifters who participated in the first Japan International Friendship Tournament in 1993. Trajectories of the barbell during snatch lifts in the competition were video-taped. Three vertical acceleration peaks of the barbell during the pull movement were observed and corresponded to the first pull transition, and second pull phases. The angle of the resultant acceleration (ARA) of the barbell averaged 85° in the first pull and transition pull phases. In the second pull phase, the ARA was almost 140°, indicating that the barbell was accelerated anteriorly, away from the lifter. The results of this study suggest that during the first pull and transition pull phases, elite lifters pulled the barbell toward themselves to produce the needed vertical acceleration and that the resulting posterior movement of the barbell was controlled by the forward acceleration produced in the second pull phase.
The Influence of Grip Position on Upper Limb Contributions to Racket Head Velocity in a Tennis Forehand
Authors: Elliott Bruce , Takahashi Kotaro , Noffal Guillermo
Published: August 2016

In tennis groundstrokes, the speed of the racket head depends on the rotational velocities of the upper limb segments and the corresponding instantaneous position of the racket. The method of holding the racket may influence these factors. Six high-performance tennis players who preferred the eastern method of holding the racket and a further 6 who preferred the western method were filmed. The displacement histories of 16 selected landmarks were calculated using the direct linear transformation approach and were used to calculate the contribution that the three-dimensional individual segment rotations for the upper limb made to racket head velocity. Horizontal flexion/abduction and internal rotation of the upper arm, in addition to linear velocity of the shoulder, were the primary contributors to racket head speed at impact, regardless of grip. Significant variations, however, were recorded for the contribution of the hand segment to racket head speed for the different grip positions.
Wave Characteristics of Olympic Breaststroke Swimmers
Authors: Sanders Ross H. , Cappaert Jane M. , Pease David L.
Published: August 2016

The purpose of this study was to investigate the wave characteristics of breaststroke swimming. Particular emphasis was accorded the question of whether modern breast-stroke is "flylike" (referring to the butterfly stroke) and whether "waves" travel along the body during the breaststroke cycle. Selected body landmarks and the center of mass (CM) of 8 Olympic breaststroke swimmers were quantified. Fourier analysis was conducted to determine the amplitude, frequency composition, and phase characteristics of the vertical undulations of the vertex of the head, shoulders, hips, knees, and ankles. The differences in phase between these landmarks for the first (HI) and second (H2) Fourier frequencies were investigated to establish whether body waves traveled in a caudal direction. While the motion of the upper body was somewhat flylike, the velocity of the HI wave from the hips to ankles was variable among subjects and, for all subjects, was too slow to be propulsive. Contrary to what one would expect, the range of vertical motion of the CM was inversely related to the range of hip vertical motion. The two highest placing subjects, based on preliminary heat times (SI and S4), were distinguished by a large range of hip vertical motion and a small range of CM vertical motion.
Shock Transmission and Fatigue in Human Running
Authors: Verbitsky Oleg , Mizrahi Joseph , Voloshin Arkady , Treiger July , Isakov Eli
Published: August 2016

The goal of this research was to analyze the effects of fatigue on the shock waves generated by foot strike. Twenty-two subjects were instrumented with an externally attached, lightweight accelerometer placed over the tibial tuberosity. The subjects ran on a treadmill for 30 min at a speed near their anaerobic threshold. Fatigue was established when the end-tidal CO2pressure decreased. The results indicated that approximately half of the subjects reached the fatigue state toward the end of the test. Whenever fatigue occurred, the peak acceleration was found to increase. It was thus concluded that there is a clear association between fatigue and increased heel strike–induced shock waves. These results have a significant implication for the etiology of running injuries, since shock wave attenuation has been previously reported to play an important role in preventing such injuries.
The Relationship between Three-Dimensional Wheelchair Propulsion Techniques and Pushing Economy
Authors: Goosey Victoria L. , Campbell Ian G. , Fowler Neil E.
Published: August 2016

Three-dimensional kinematic and physiological data were obtained from 18 wheelchair racers, to allow the relationship between pushing economy and kinematic variables at 4.70 m · s−1(n= 18) and 6.58 m · s−1(n= 12) to be examined. Large inter individual differences in wheelchair propulsion styles were present, which made it difficult to identify variables that were associated with pushing economy and indeed to distinguish key variables that were characteristic of an economical wheelchair racer. Furthermore, those variables associated with economy proved inconsistent across the two speeds. However, at both speeds a higher mechanical efficiency and lower push rate were associated with better economy (p< .05). It was also found that the timing parameters were important. In this respect most athletes tended to push through a similar push angle; however, push rate differed between individuals, suggesting that the magnitude and direction of the hand-rim forces may be important for determining economy of propulsion.
Investigating Kinetics in the Freestyle Flip Turn Push-Off
Authors: Lyttle Andrew D. , Blanksby Brian A. , Elliott Bruce C. , Lloyd David G.
Published: August 2016

Thirty experienced male swimmers with body types ± 1 SD of the mean of selected body form parameters reported for elite male swimmers were recruited for the study. During three freestyle flip turns, selected kinetic, hydrodynamic, and kinematic variables of the push-off following a flip turn were recorded. Kinetics were recorded via a 2D vertically mounted forceplate that recorded peak push-off force and total impulse. The acceleration of each swimmer’s center of gravity and wall exit velocity were calculated from underwater videography. Hydrodynamic peak drag force and drag impulse were calculated from the kinetic and kinematic data using a derivative of Newton’s second law. A stepwise regression yielded peak drag force, peak propulsive force, and push-off time in the final regression equation (R = 0.80; R2 = 0.64). Beta values indicated that the peak drag force carried the highest weighting of the three variables. The results of the stepwise regression indicated that a combination of a low peak drag force high peak propulsive force, and increased wall push-off time produced the fastest final push-off velocity.
A Procedure for the Automatic Determination of Filter Cutoff Frequency for the Processing of Biomechanical Data
Authors: Challis John H.
Published: August 2016

This article presents and evaluates a new procedure that automatically determines the cutoff frequency for the low-pass filtering of biomechanical data. The cutoff frequency was estimated by exploiting the properties of the autocorrelation function of white noise. The new procedure systematically varies the cutoff frequency of a Butterworth filter until the signal representing the difference between the filtered and unfiltered data is the best approximation to white noise as assessed using the autocorrelation function. The procedure was evaluated using signals generated from mathematical functions. Noise was added to these signals so mat they approximated signals arising from me analysis of human movement. The optimal cutoff frequency was computed by finding the cutoff frequency that gave me smallest difference between the estimated and true signal values. The new procedure produced similar cutoff frequencies and root mean square differences to me optimal values, for me zeroth, first and second derivatives of the signals. On the data sets investigated, this new procedure performed very similarly to the generalized cross-validated quintic spline.
Evaluation of Knee Extensor Muscles under Non-Isokinetic Conditions in Elderly Subjects
Authors: Rahmani Abderrehmane , Belli Alain , Kostka Tomasz , Dalleau Georges , Bonnefoy Marc , Lacour Jean-Rene
Published: August 2016

This paper describes the application of the inverse dynamic method developed by Bosco and colleagues for measuring the mechanical properties of knee extensor muscles under ballistic conditions. Twenty elderly men performed a series of maximal ballistic leg extensions at different loads. Accurate measurements of friction and inertial effects during the movement were used to calculate the torque and power produced during extension. The error of the results was 6.2–45.3% when the friction and inertial effects were neglected. The torque-angular velocity relationships were linear (r = 0.92 to 0.99, p < .001). The peak measurements obtained were in agreement with published isokinetic values. This new ergometer allows assessment of movements similar to those performed in day-to-day activities and can be used. without training, by elderly or disabled subjects.
Architecture of Contracting Human Muscles and Its Functional Significance
Authors: Kawakami Yasuo , Ichinose Yoshiho , Kubo Keitaro , Ito Masamitsu , Imai Morihiro , Fukunaga Tetsuo
Published: August 2016

This paper reviews three of our recent studies on human muscle architecture in vivo. 1. Hypertrophic changes: From B-mode ultrasonograms, pennation angles and thickness of triceps brachii were determined for normal subjects and highly-trained bodybuilders. There was a significant correlation between muscle thickness and pennation angles. It was confirmed that hypertrophy was accompanied by an increase in pennation angles. 2. Variation of fascicle architecture: Fascicle lengths and pennation angles were obtained from different positions in the gastrocnemius muscle while the subjects relaxed and performed isometric plantar flexion. The fascicle length was uniform throughout the muscle and shortened by contraction (30-34% at 50% of the maximal force). On the other hand, pennation angles differed among positions and increased by contraction. The muscle thickness did not change by contraction. Pen-nation angles were significantly correlated with muscle thickness within muscle. 3. Joint position-fascicle length relationships: Ultrasonic images of the gastrocnemius and soleus muscles were obtained while the subject performed maximal isometric plantarflexion at various joint positions, from which fascicle lengths and angles were determined. The length-force relationship of each muscle was estimated. It was suggested that human muscle architecture has an ability to make substantial changes to adapt to environmental conditions.
The Effect of Postural Variations in Movement Co-Ordination during Plyometric Rebound Exercises
Authors: Felix Rodacki André Luiz , Fowler Neil Edward , Bennett Simon
Published: August 2016

The aim of this study was to compare the kinematic pattern and the segmental movement co-ordination when the trunk segment was constrained in different positions during plyometric rebound jumps. Nine skilled volleyball players, experienced in plyometric training, were asked to perform a random series of maximal rebound jumps, using three different seat arrangements (90°, 135°, and 180°) in a pendulum swing device. From two-dimensional filming, performed in a right sagittal plane at 200 Hz, it was possible to calculate ankle, knee, and hip displacements; velocities; and muscle-tendon lengths. The subjects showed similar ankle and knee angles between experimental conditions. The hip joint angle differed significantly between conditions. Only the muscle-tendon lengths of the biarticular muscles spanning the knee/hip were affected by the seat arrangement variations. Significantly greater knee angular velocities were observed in the upright sitting posture (90°). The hip was consistently the first joint to extend. The ankle and knee joint reversals were not invariant, regardless of the seat arrangement. The movement co-ordination strategy did not differ across postural variations.
Quantifying Force Magnitude and Loading Rate from Drop Landings That Induce Osteogenesis
Authors: Bauer Jeremy J. , Fuchs Robyn K. , Smith Gerald A. , Snow Christine M.
Published: August 2016

Drop landings increase hip bone mass in children. However, force characteristics from these landings have not been studied. We evaluated ground and hip joint reaction forces, average loading rates, and changes across multiple trials from drop landings associated with osteogenesis in children. Thirteen prepubescent children who had previously participated in a bone loading program volunteered for testing. They performed 100 drop landings onto a force plate. Ground reaction forces (GRF) and two-dimensional kinematic data were recorded. Hip joint reaction forces were calculated using inverse dynamics. Maximum GRF were 8.5 ± 2.2 body weight (BW). At initial contact, GRF were 5.6 ± 1.4 BW while hip joint reactions were 4.7 ± 1.4 BW. Average loading rates for GRF were 472 ± 168 BW/s. Ground reaction forces did not change significantly across trials for the group. However, 5 individuals showed changes in max GRF across trials. Our data indicate that GRF are attenuated 19% to the hip at the first impact peak and 49% at the second impact peak. Given the skeletal response from the drop landing protocol and our analysis of the associated force magnitudes and average loading rates, we now have a data point on the response surface for future study of various combinations of force, rate, and number of load repetitions for increasing bone in children.
High Resolution Determination of Body Segment Inertial Parameters and Their Variation Due to Soft Tissue Motion
Authors: Pain Matthew T.G. , Challis John H.
Published: August 2016

This study had two purposes: to evaluate a new method for measuring segmental dimensions for determining body segment inertial parameters (BSIP), and to evaluate the changes in mass distribution within a limb as a consequence of muscular contraction. BSIP were calculated by obtaining surface data points of the body under investigation using a sonic digitizer, interpolating them into a regular grid, and then using Green’s theorem which relates surface to volume integrals. Four skilled operators measured a test object; the error was approximately 2.5% and repeatability was 1.4% (coefficient of variation) in the determination of BSIP. Six operators took repeat measures on human lower legs; coefficients of variation were typically around 5%, and 3% for the more skilled operators. Location of the center of mass of the lower leg was found to move up 1.7 cm proximally when the triceps surae muscles went from a relaxed state to causing plantar flexion. The force during an impact associated with such motion of the soft tissue of the lower leg was estimated to be up to 300 N. In summary, a new repeatable and accurate method for determining BSIP has been developed, and has been used to evaluate body segment mass redistribution due to muscular contraction.
Elbow Flexor Inhibition as a Function of Muscle Length
Authors: Brondino Luciana , Suter Esther , Lee Hae-Dong , Herzog Walter
Published: August 2016

Muscle inhibition (MI) in human knee extensors increases with increasing maximal voluntary force as a function of knee angle. It was speculated that this angle-dependent MI was modulated by force-dependent feedback, likely Golgi tendon organ pathways. Such angle-dependent MI is of clinical and theoretical importance. The purpose of this study was to determine MI in human elbow flexors for maximal voluntary contractions. Muscle inhibition, elbow flexor force, and electromyographic (EMG) activity were measured in 31 volunteers at elbow angles between 30º and 120º. MI and elbow flexor EMG were the same at all elbow angles. Maximal isometric forces were greatest at the 70º angle, and never fell below 70% of the peak force at any of the tested angles. From these results it is concluded that force-dependent modulation of MI did not occur in the elbow flexors, possibly because maximal isometric force remained relatively close (within 30%) to the peak force. In contrast, force-dependent modulation of MI occurred in the knee extensors at the most extended angles, when the average knee extensor force had dropped to 50% or less of the maximal knee extensor force. It is likely that human maximal voluntary contractions are not associated with a given activation. Rather, activation appears to be modulated by force-dependent feedback at force levels below 70% of the absolute peak force, which manifests itself in a change of MI that parallels the level of maximal isometric force in voluntary contractions.
Stability of Selected Lower Limb Joint Kinetic Parameters during Vertical Jump
Authors: Rodano Renato , Squadrone Roberto
Published: August 2016

Stability and consistency is a critical aspect in joint kinetic measurements. By applying a statistical technique, called sequential estimation procedure, the aim of this work was to determine the minimum number of trials required to obtain a stable mean for peak hip, knee, and ankle moments and powers during vertical jump. Nine competitive track and field sprinters (21.7 ± 3.5 yrs, 177.6 ± 4.3 cm, 70.8 ± 3.6 kg) performed 5 series of 5 double-legged maximum-height countermovement vertical jumps. From force platform and kinematic data, moment and power output were calculated for hip, knee, and ankle joints. The sequential estimation procedure applied to these data revealed that at least a 12-trial protocol is needed to establish a true measure for all the selected parameters. The mean number of trials for each variable was greater than 8 and less than 13. When hip moments were excluded from the analysis, a 10-trial protocol could be sufficient to reach a stable mean. In conclusion. the results of this study gave statistical evidence for the need to adopt multiple-trial protocols in order to obtain a stable mean for joint kinetic data.