THE EFFECT OF HIGH-INTENSITY INTERVAL CYCLINGSPRINTS SUBSEQUENT TO ARM-CURL EXERCISE ON
UPPER-BODY MUSCLE STRENGTH AND HYPERTROPHYNAOKI KIKUCHI,1 SHOU YOSHIDA,2 MIZUKI OKUYAMA,3 AND KOICHI NAKAZATO2
1

Sports Training Center, Nippon Sport Science University, Tokyo, Japan; 2Department of Exercise Physiology, Nippon Sport Science
University, Tokyo, Japan; and 3Graduate School of Health and Sport Science, Nippon Sport Science University, Tokyo, Japan

ABSTRACTINTRODUCTION

Kikuchi, N, Yoshida, S, Okuyama, M, and Nakazato, K. The
effect of high-intensity interval cycling sprints subsequent toarm-curl exercise on upper-body muscle strength and hypertrophy. J Strength Cond Res 30(8): 2318–2323, 2016—The
purpose of this study was to examine whether lower limb sprintinterval training (SIT) after arm resistance training (RT) influences training response of arm muscle strength and hypertrophy.
Twenty men participated in this study. We divided subjects into
RT group (n = 6) and concurrent training group (CT, n = 6).
The RT program was designed to induce muscular hypertrophy(3 sets 3 10 repetitions [reps] at 80% 1 repetition maximum[1RM] of arm-curl exercise) and was performed in an 8-weektraining schedule performed 3 times per week on nonconsecutive days. Subjects assigned to the CT group performed identical protocols as strength training and modified SIT (4 sets of
30-s maximal effort, separated in 4 m 30-s rest intervals) on thesame day. Pretest and posttest maximal oxygen consumption(V_ O2max), muscle cross-sectional area (CSA), and 1RM were
measured. Significant increase in V_ O2max from pretest to posttest was observed in the CT group (p = 0.010, effect size
[ES] = 1.84) but not in the RT group (p = 0.559, ES =0.35). Significant increase in CSA from pretest to posttest
was observed in the RT group (p = 0.030, ES = 1.49) but
not in the CT group (p = 0.110, ES = 1.01). Significant
increase in 1RM from pretest to posttest was observed in
the RT group (p = 0.021, ES = 1.57) but not in the CT group(p = 0.065, ES = 1.19). In conclusion, our data indicate that
concurrent lower limb SIT interferes with arm muscle hypertrophy and strength.

KEY WORDS concurrent training, endurance, sprint interval
training, systemic effects

Address correspondence to Naoki Kikuchi, naoki.k@live.jp.
30(8)/2318–2323
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T

he concomitant integration of resistance andendurance training is termed concurrent training(CT). Many sports require the improvement ofmuscular strength, power, and size, and endurance
simultaneously for success. However, previous studies reported that CT relative to resistance training (RT) alone
resulted in decrement in strength (7,11,14), hypertrophy(11,14), and power (14).
A recent review indicated that interference effects of CT
are associated with training variants such as exercise
modality, frequency, and duration of the endurance training(21). Jones et al. (12) reported the effect of differing ratios oftime spent in each strength and endurance exercise modality
per session on adaptation of muscle strength and hypertrophy. The results suggested that a protocol of an endurance
and strength training (ST) ratio of 3:1 increased the magnitude of the interference response on strength and hypertrophy compared with a protocol of ST only, or an endurance
and ST ratio of 1:1, after 3 times per week for 6 weeks. Theirfindings indicate that the ratio of endurance to ST performed
during CT influences the degree of interference. Therefore,
maintaining the volume and duration of endurance training
is important if the primary focus of the training intervention
is improving strength and hypertrophy.
Previous studies for investigating CT have implemented
continuous or interval endurance training before or subsequent to ST. Recently, many studies suggested that highintensity endurance exercise, specifically sprint interval
training (SIT), results in similar adaptations as lowintensity, high-volume endurance training (4,9). These studies demonstrated significant improvements in peak oxygen
uptake at a substantially less training volume. In fact, theweekly training volume for SIT was ;90% lower than thatfor the continuous endurance training group (i.e., 225 vs.
2,250 kJ) (4). Therefore, in addition to similar physiological
adaptations, SIT may be an optimal complement to ST ina CT program. Recently, Cantrell et al. (5) suggested that
separate days of concurrent strength and SIT, such as ST,
will not interfere with muscle hypertrophy and strength. To
our knowledge, no data exist which examine chronic

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physiological adaptations (i.e., muscle cross-sectional area
[CSA] and 1 repetition maximum [1RM]) to the same day
protocol of concurrent sprint interval and ST.
In addition, it is well known that a cross-transfer effect(20), which provides increased exercise performance during exercise with the untrained limbs or parts, exists instrength and aerobic exercises. Pogliaghi et al. (16) evaluated the effect of upper-body endurance training (armcranking) and low-body endurance training (cycling training) for 12 weeks on maximal and submaximal exercise
capacity of each untrained limb in elderly subjects. They
reported a significant effect of arm cranking and cycling
training on both peak and submaximal untrained limb performance, which increased by 10% of pretraining values ineach group (13). These results suggest that nonspecificimprovement of aerobic capacity occurs independent of
which muscle is exercised. In a practical sense, it is usualthat arm ST and aerobic bike training are performed ina same training session. Thus, we wished to know whether
ST performed in one body part is affected by aerobic training performed in another part.
Previous studies evaluated concurrent lower-body ST
and lower-body endurance training (10,15), or concurrent
whole-body ST and lower-body endurance training (7,12).
Dolezal and Potteiger (7) reported concurrent interference
as follows: eight weeks of concurrent whole-body ST andlower-body endurance training were observed to lower
the percent change of 1RM bench press (12%) comparedwith the ST only group (24%). Dolezal and Potteiger (7)suggest that the cross-transfer effect (20) increases exercise
performance during exercise with the untrained limbs andshould be considered as one of the causes of concurrent
interference.
The purpose of this study was to examine whether highintensity interval cycling sprints and subsequent upper-body
ST influence training response of muscle strength andhypertrophy. We hypothesized that SIT, which is lower intotal volume than that of traditional endurance training,
subsequent to ST, does not interfere with muscle hypertrophy and strength. We also tested whether sprint training
performed with the lower limbs influenced arm ST by thecross-transfer effect (20).

METHODS
Experimental Approach to the Problem

Subjects were randomly assigned to the experimental group:
concurrent resistance and sprint interval group (CT) and RT
alone group. A supervised progressive RT program designed
to induce muscular hypertrophy (3 sets of 10 repetitions[reps] at 80% 1RM of bilateral arm-curl exercise) was
performed in 8 weeks, with training performed 3 times per
week on nonconsecutive days. Subjects assigned to the CT
group performed protocols identical to the ST and modified
SIT group, with 4 sets of 30-s maximum sprint, on the sameday. One repetition maximum, muscle CSA, and maximal

oxygen consumption (V_ O2max) were measured pretraining
and posttraining in both groups. All testing and training
were supervised by a National Strength and Conditioning
Association, Certified Strength and Conditioning Specialist(NSCA–CSCS).
Subjects

Fourteen Japanese male subjects (age, 20 6 1.8 years; age
range, 18 to 22 years; height, 171.2 6 4.9 cm; weight, 64.5
6 4.7) volunteered to participate in this study. All participants had previous experience in weight training. Two
subjects did not complete all training sessions, providing
no explanation. None of the subjects was taking any medication. All the participants were informed about the potential risks of the experiment and gave their written consent
to participate in the experiment. The study was approvedby the ethics committee of Nippon Sport Science University and was in accordance with the Declaration of Helsinki
for Human Research.
Procedures

Training Protocol. Resistance Training Group. A
supervised progressive RT program designed to induce
muscular hypertrophy (3 sets of 10 reps at 80% 1RM ofbilateral arm-curl exercise, separated 90-second rest intervals) was performed for 8 weeks using arm-curl machine,with training performed 3 times per week on nonconsecutive
days (Figure 1). A warm-up set of 8–10 repetitions was performed at 50% of the individual’s measured maximum. The
subjects perform to failure in the final set. The subjects perform to the training intensity was increased 5% over baseline
1RM if the final working set exceeded 12 repetitions ina given workout. All subjects were individually supervisedby experienced instructors during each training session to
reduce deviations from the study protocol and to ensure
subject safety.

Concurrent Training Group. The SIT was performed in 4 sets of 30-s maximal effort, separated in 4 m
30-s rest intervals, on a PowerMaxV II (Combi, Tokyo,
Japan) using a resistance equal to 7.5% of the subject’s bodyweight. Each subject was then given a 3–5 minutes of warmup period on a cycle ergometer, whereby they strived toachieve a warm-up heart rate of 130–140 b$min21. Subjects
assigned to the CT group performed protocols identical to
the ST and modified SIT group, on the same day.
One Repetition Maximum. All subjects performed thetest of 1RM using the arm-curl machine. Before the test,
subjects were given instructions on proper techniques andtest procedures. After a warm-up consisting of several sets of
6–10 repetitions using a light load, each participant attempted a single repetition with a load believed to be approximately 90% of his/her maximum. If the attempt was
successful, weight was added depending on the ease withwhich the single repetition was completed. If the attempt
was not successful, weight was removed from the bar.
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Concurrent Interval Sprints and Strength Training

Figure 1. The arm-curl machine used in this study (A), the starting position of arm-curl exercise (B), and final position (C).

A minimum of 3 minutes of rest was allowed between maximal attempts. This procedure continued until the participant was not able to complete a single repetition throughthe full range of motion. A subject’s 1RM was consideredwhen the exercise could be performed in proper form using
the heaviest load and was usually achieved in 3–5 attempts.

Muscle Cross-Sectional Area. Using a 0.3 T magnetic
resonance (MR) system AIRIS II (HITACHI, Tokyo, Japan),the CSAs of the femoral muscle were calculated using T1weighted cross-sectional images of the upper arm at 50% area
between the lateral epicondyle of the humerus and acromial
process of the scapula (spin echo method; repetition time, 700

milliseconds; echo time, 20 milliseconds; and slice thickness
and slice space, 10 mm). Among the 3 slices (50% of upper
arm, 10 mm distal, and 10 mm proximal), the muscle CSA of
the biceps and the brachialis was calculated twice by the sameinvestigator, and the mean value was used for subsequentcalculations. The CSA of each muscle was traced andcalculated by Image J computer software (National Institutesof Health, Bethesda, MD, USA).
V_ O2max. A maximal graded exercise test was performed ona cycle ergometer (PowerMaxV II; Combi) to measure
V_ O2max. After a warm-up consisting of several minutes using
light resistance, subjects began the test at 100 W with an

TABLE 1. Effect on V_ O2max, CSA, 1RM, and body weight of 8 weeks of concurrent training (n = 6) and resistancetraining alone (n = 6).*†
Parameter tested
V_ O2max (ml$kg21$min21)z
CSA (cm2)
1RM (kg)kBody weight (kg)Training Condition

Pretreatment

Posttreatmentp

ES (95% CI)

CT
RT
CT
RT
CT
RT
CT
RT

51.3 6 6.3
51.8 6 5.9
13.6 6 1.4
14.2 6 2.0
19.2 6 5.6
21.7 6 4.1
63.3 6 4.1
65.6 6 5.4

63.0 6 6.4
54.7 6 10.0
16.3 6 3.5
16.6 6 1.1
27.5 6 8.1
29.6 6 5.8
63.3 6 2.1
65.0 6 6.3

0.010§
0.559
0.110
0.030§
0.065
0.021
0.993
0.866

1.84 (0.38 to 3.02)
0.35 (20.81 to 1.47)
1.01 (20.26 to 2.13)
1.49 (0.11 to 2.63)
1.19 (20.11 to 2.31)
1.57 (0.18 to 2.72)
0.00 (21.13 to 1.13)
20.10 (21.24 to 1.04)_ O2max = maximal oxygen consumption; CSA = cross-sectional area of muscle; 1RM = 1 repetition maximum; ES = effect size;*V
95% CI = 95% confidence interval; CT = concurrent training; RT = resistance training.
†Values are mean 6 SD.
zp # 0.05 significant interaction effect by 2-way analysis of variance (ANOVA).
§p # 0.05 significant difference after training by Bonferroni post hoc test.
kp # 0.05 significant main effect (time) by 2-way ANOVA.

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TABLE 2. Individual training response of V_ O2, CSA, and 1RM in CT and RT group.*
V_ O2max (ml$kg21$min21)
Training Condition
Subject ACT
Subject B
CT
Subject CCT
Subject DCT
Subject E
CT
Subject FCT
Subject G
RT
Subject H
RT
Subject I
RT
Subject J
RT
Subject K
RT
Subject L
RT

CSA (cm2)

1RM (kg)

Pre

Post

Pre

Post

Pre

Post

49.6

62.3

14.3

17.5

15.0

25.0

57.2

69.4

15.7

22.2

20.0

30.0

52.3

61.3

13.4

13.8

15.0

25.0

46.8

61.3

13.3

16.8

17.5

22.5

59.2

70.6

11.4

11.4

17.5

20.0

42.6

52.9

13.8

12.4

30.0

42.5

48.0

51.1

17.3

17.2

20.0

30.0

55.5

63.1

11.9

16.2

20.0

30.0

60.5

66.3

12.4

17.5

20.0

27.5

54.0

60.0

13.5

15.5

20.0

28.0

48.8

41.3

15.6

16.5

20.0

22.5

44.1

46.3

14.7

15.8

30.0

40.0

_ O2max = maximal oxygen consumption; CSA = cross-sectional area of muscle; 1RM = 1 repetition maximum; CT = concurrent*V
training; RT = resistance training.

increase of 20 W every minute thereafter. Pedaling rate wasmaintained between 55 and 65 RPM throughout the test.
Expired gases were collected and analyzed by AE100i (Minato, Tokyo, Japan).
Statistical Analyses

The SPSS statistical package, version 22.0 for mac, was used
to perform all the statistical evaluations. A two-way analysis
of variance (ANOVA) (group vs. time) with repeatedmeasures was performed to assess training-related differences in the ST and CT groups for each dependent variable.
In addition, the Bonferroni post hoc test was performed toevaluate training-related changes within groups. Cohen’sd effect sizes (ES), reported for all observations, with
#0.20 representing a small effect, 0.50 representing
a medium effect, and $0.80 representing a large effect (6),were estimated to compare with the magnitude of the training response. The level of significance was set at p # 0.05.

RESULTSOf the 14 subjects enrolled in the study, 12 successfully
finished and were included in the analyses. Pretest andposttest V_ O2max, CSA, and 1RM are shown in Tables 1 and
2. No differences were observed between groups in allparameters at baseline. An interaction effect was observedin V_ O2max (p = 0.001) but not in CSA and 1RM. In addition,a significant Mein effect (Time) was observed in only 1RM
using a 2-way ANOVA. Significant increase in V_ O2max frompretest to posttest was observed in the CT group (p = 0.010,
ES = 1.84, 95% confidence interval [CI]: 0.38–3.02) but notin the RT group (p = 0.559, ES = 0.35, 95% CI: 20.81 to1.47). Significant increase in CSA from pretest to posttest
was observed in the RT group (p = 0.030, ES = 1.49, 95%
CI: 011–2.63) but not in the CT group (p = 0.110, ES = 1.01,
95% CI: 20.26 to 2.13). Significant increase in 1RM frompretest to posttest was observed in the RT group (p = 0.021,
ES = 1.57, 95% CI: 0.18–2.72) but not in the CT groups (p =0.065, ES = 1.19, 95% CI: 20.11 to 2.31). There was no
significant change of body weight from pretest to posttest
in both groups.

DISCUSSION
This study examined whether high-intensity interval cycling
sprints before upper-body RT influences the training
response of muscle strength and hypertrophy. We hypothesized that high-intensity and low-volume interval cycling
sprint compared with traditional endurance training (9)VOLUME 30 | NUMBER 8 | AUGUST 2016 |2321

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Concurrent Interval Sprints and Strength Training
subsequent to ST does not interfere with muscle hypertrophy and strength. However, our data might indicate that
concurrent upper-body ST and sprint interval cycling sprints
on the same day interfere with muscle hypertrophy andstrength caused by systemic factors.
Previous research demonstrated that CT, relative to RT
only, results in compromised strength (7,11,14), hypertrophy(14), and power development (14). Conversely, RT seems tohave little to no negative impact on endurance performanceand V_ O2max (21). In addition, Silva et al. (19) reported that
CT performed twice a week promotes similar neuromuscular
adaptations to ST alone and to concurrent strength combined with one of three types of aerobic training (continuous
running, continuous cycling, and interval running) in young
women. Our results were in agreement with these previous
studies but against our hypothesis.
As a potential mechanism for local factors causing
concurrent interference, the activity of selected negative
regulators of protein synthesis, such as AMP-activatedprotein kinase (AMPK) and eukaryotic translation initiation
factor-4E-binding protein 1 (4E-BP1), is increased byendurance exercise in an intensity-dependent manner (18).
Moreover, previous studies suggest that AMPK activation
has a significant inhibitory effect on mammalian target of
rapamycin complex 1 (mTORC1) and its downstream signaling targets, thereby negatively regulating protein synthesis and hypertrophy (2,3). Recently, high-intensity interval
training has been reported as a potent exercise strategy for
inducing signaling related to mitochondrial biogenesis, withassociated health benefits and athletic performance (8).
Taken together, these studies provide convincing evidence
that higher intensity interval training exacerbates acutemolecular interference with muscle hypertrophy inducedby RT.
As mentioned above, the best characterized local interference mechanism of CT is an antagonistic interaction
between the AMPK and mTORC1 signaling (2). However,
Apro et al. showed that the signaling of muscle growththrough the mTORC1-S6K1 axis after high-intensity andhigh-volume resistance exercise is not inhibited by subsequent endurance exercise (1). It is possible that a regimen
of previous RT alters hypertrophic response after an overall
CT session.
The systemic factors responsible for concurrent interference with muscle hypertrophy and strength are not clearly
known. We hypothesized that concurrent interference due
to systemic factors would also be associated with interfering
AMPK activity for mTOR signaling in upper-body muscle
during and/or after high sprint lower-body exercise. We
suggest 2 of possible mechanisms, one involves the creatine(Cr) concentration and the other involves reactive oxygen
species (RONS). High-intensity RT decreases the concentration of phosphocreatine (PCr) in trained muscle, and thisis restored after training (10). Ponticos et al. (17) suggested
that AMPK activity is activated by permanently high levels

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of Cr in the muscle. Slow recovery of increased Cr after RT
might activate AMPK. High blood flow in arm muscles isrequired for early recovery of PCr after exercise, but it should
be decreased during high sprint leg exercise because of blood
redistribution (13). Therefore, we believed that recovery of
PCr concentration after RT in upper-body muscle might not
be sufficient after high-intensity lower-body endurance exercise. The slow recovery of Cr might activate AMPK.
Another possible factor for systemic concurrent interferenceis the effect of RONS (15). The RONS are produced during
exercise, such as the Wingate test, and play a role in regulating calcium calmodulin kinase (CaMK)-AMPK axis signaling pathway (15). We suspect that RONS produced bysprint leg exercise diffuse systemically and interfere with
mTOR activation in arm muscles. Because the findings
shown in this study suggest that concurrent interference
occur systemically, we will investigate mechanisms such as
Cr metabolisms, RONS productions, etc. We believe that the
key is to interfere with mTOR signaling during concurrent
upper-body ST and lower-body high-intensity interval
exercise.
In this study, there are several limitations. The first is oursmall sample size. Therefore, the chance of committinga type II error in evaluating our measurements was high.
Second, we could not control for nutrition factors such as
diet and intake of supplements, which could influence theresults of our study. We could not evaluate muscle volume, as
we only measured a single site of arm CSA. In addition, our
exercise protocol (arm-curl exercise) was minimalistic. It
would be assumed that greater interference would be foundwhen higher volume protocols are used, particularly involving large, multijoint movements.
In conclusion, our data of a pilot study may indicate that
concurrent strength and SIT interfere with muscle hypertrophy and strength, if performed on the same day.

PRACTICAL APPLICATIONSIn this study, the CT group performed SIT immediately after
RT. A recent review reported that concurrent strength andendurance training on the same day have higher effect on
hypertrophy and strength responses than the two trainings
on separate days, although this difference was not statistically significant (21). Cantrell et al. (5) examined the chronic
effect of concurrent strength and SIT on strength and hypertrophy on separate days. They suggested that SIT performed
concurrently with heavy ST on separate days does not seemto interfere with the development of maximal strength. In
addition, aerobic performance seems to respond positively to
low-volume, high-intensity SIT. These studies indicate theinfluence of duration of session interval between RT and
endurance training, and the order of exercise performance,on the effects of CT. One explanation could be that endurance training after hypertrophic molecular response does notinterfere with anabolic adaptation for RT, considering thatnumerous animal and human studies have shown activation

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of mTORC1 signaling in response to ST more than 24 hours
after resistance exercise.

10. Goreham, C, Green, HJ, Ball-Burnett, M, and Ranney, D. Highresistance training and muscle metabolism during prolonged
exercise. Am J Physiol 276: E489–E496, 1999.

ACKNOWLEDGMENTS

11. Hickson, RC. Interference of strength development by
simultaneously training for strength and endurance. Eur J Appl
Physiol Occup Physiol 45: 255–263, 1980.

This work was supported by a Grant-in-Aid for Young
Scientists (B15K16467 to N.K.) from the Ministry of
Education, Culture, Sports, Science, and Technology.

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