# The Physiological Characteristics of an 83-Year-Old Champion Female Master Runner

Thomas Cattagni, Vincent Grémeaux, Romuald Lepers

► To cite this version:

Thomas Cattagni, Vincent Grémeaux, Romuald Lepers. The Physiological Characteristics of an 83-Year-Old Champion Female Master Runner. International Journal of Sports Physiology and Performance, In press, 15 (3), pp.444-448. 10.1123/ijspp.2018-0879. hal-02889378

HAL Id: hal-02889378

https://u-bourgogne.hal.science/hal-02889378

Submitted on 27 Apr 2023

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.
1

The physiological characteristics of an 83-year-old champion female master runner

2

3

4

Thomas CATTAGNI¹, Vincent GREMEAUX ²,³,⁴, Romuald LEPERS ⁵

5

6

¹ Inserm Unit 1179, Team 3: Technologies and Innovative Therapies Applied to Neuromuscular diseases, UVSQ. CIC 805, Physiology-Functional Testing Ward, AP-HP, Raymond Poincaré Teaching Hospital, Garches, France.

7

8

9

² Swiss olympic medical center, Division de médecine physique et réadaptation, CHUV, 1011

10

Lausanne

11

³ Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland.

12

⁴ Pôle Rééducation-Réadaptation, CHU Dijon, France.

13

⁵ INSERM UMR1093-CAPS, Université Bourgogne Franche-Comté, UFR des Sciences du

14

Sport, F-21000, Dijon

15

16

Corresponding author:

17

Thomas Cattagni

18

Hôpital Raymond Poincaré

19

104 bd Raymond Poincaré

20

92380, Garches

21

France

22

Email: thomas.cattagni@uvsq.fr

23

Tel: +33 1.47.10.79.00
24 **ABSTRACT**

**Purpose:** To examine the cardiorespiratory, muscular and skeletal characteristics of an 83-year-old champion female master athlete (called DL in this study) who had set multiple world running records in the 80-to-84-year-old age group. **Methods:** Measures of maximal oxygen uptake (VO₂max), maximal heart rate (HRmax), maximal isometric torque for knee extensor muscles, thigh and triceps surae muscle volumes, and bone mineral density (BMD) of the proximal femur region were evaluated. Based on previously published equations, physiological age was determined for VO₂max, HRmax and maximal isometric torque. Muscle volumes for the dominant leg were compared with previously published sex- and age-matched data using Z-scores. For BMD, T-score and Z-score were calculated. **Results:** DL had the highest VO₂max (42.3 ml·min⁻¹·kg⁻¹) ever observed for a female over 80 years of age, which gave her a remarkable physiological age (27 years). In contrast, she had a physiological age closer to her biological age for maximal isometric torque (90 years) and HRmax (74 years). The Z-scores for thigh (0.4) and triceps surae (1.1) muscle volumes revealed that DL's leg muscles were affected almost as much as her sex- and age-matched peers. The T-score (-1.7) for BMD showed that DL had osteopenia but no osteoporosis, and the Z-score (0.7) showed that DL's BMD was similar to that of females of the same age. **Conclusions:** This single case study shows that the remarkable cardiorespiratory fitness coupled with intensive endurance training observed in a female master athlete was not associated with specific preservation of her muscular and skeletal characteristics.

44

45 **KEYWORDS**

46 Cardiorespiratory fitness; Neuromuscular function; Maximal oxygen uptake; Bone mineral 47 density; MRI.

48

49 **INTRODUCTION**

50 Master athletes, being free from the negative influence of physical inactivity, are considered as 51 models for primary biological aging.¹ Study of the physiological characteristics of high- 52 performance master athletes is essential to improve knowledge about the limits of human 53 physiology with age.

54 With performance in athletic endurance events being mainly related to aerobic capacity, master 55 athletes generally present with well-preserved aerobic capacity, as revealed by their high levels 56 of maximal oxygen uptake (VO2max). VO2max values of approximately 40-45 ml·kg⁻¹·min⁻¹ 57 (comparable with that observed in sedentary young healthy males) have been reported in 65- 58 to-80-year-old champion male athletes,²,³ while only ~20-to-25 ml·kg⁻¹·min⁻¹ is generally 59 observed in age-matched untrained people.⁴ Two studies even reported a VO2max of 50 ml·kg⁻ 60 ¹·min⁻¹ for an 80-year-old male,⁵ and a master runner with multiple world records.⁶ Female 61 master athletes aged between 60 and 70 years presented a VO2max of approximately 38 ml·kg⁻ 62 ¹·min⁻¹.⁷ Like males, their VO2max is comparable to their younger sedentary counterparts 63 [VO2max: ~30-35 ml·kg⁻¹·min⁻¹]⁴ and considerably higher than their less physically active age- 64 matched peers [VO2max: ~16-21 ml·kg⁻¹·min⁻¹].⁴ To date, the VO2max of female master athletes 65 aged over 70-80 years is poorly documented and the VO2max of the most elite remains to be 66 investigated to estimate the maximum limit of aerobic capacity in older females.

67 While aerobic capacity is known to be related to cardiovascular health, it is also related to 68 skeletal muscle health.⁸ However, a recent meta-analysis revealed that age-related declines in 69 muscular strength were not prevented in male master athletes competing in endurance events.⁹ 70 In addition, while males and females may undergo somewhat divergent deterioration of skeletal 71 muscle function with advancing age, perhaps due to reductions in sex-specific hormones, most 72 conclusions regarding the skeletal muscle function of master athletes have been based on data
collected in males only.⁹,¹⁰ The skeletal muscle characteristics of older female master athletes
thus remain to be investigated.

While the benefits of chronic endurance exercise have been observed in cardiovascular and
muscle function, the benefit for skeletal function is not clear. Wiswell et al.¹¹ showed that
bone mineral density can be maintained by running in older active males. In contrast, no
specific protection of bone mineral density (BMD) was observed in post-menopausal female
master runners.¹² However, it is not known whether this lack of bone protection is also observed
in female master runners with very high fitness levels.

This case study aimed to present and compare some physiological characteristics of a champion
female master runner (called DL in this study) with those of females of the same age.

83

## MATERIALS AND METHOD

### Subject

At the time of the evaluation (June 2017), DL was 83 years old. She was a French Caucasian retired beautician, living in Burgundy, France. Her anthropometric characteristics are displayed in Table 1. DL had broken three world records (3,000, 5,000 and 10,000 m running) in the 80-to-84-year-old age-group category, by the age of 80. For example, her record in 10,000 m outdoor running was 0:55:26. She was still taking part in both walking and running competitions at the time of evaluation. DL volunteered and was informed about the nature and aims of the study, as well as the associated risks and discomfort prior to giving her written consent to participate in the investigation. The protocol was in conformity with the Declaration of Helsinki (last modified in 2013).

95

Typical training and competition schedule (S.1), sport history (S.2), medical history (S.3), and
athletics performances/records (Supplemental Table 1) of DL are available as an online
supplement.

99

## Experimental procedure, measurements & data analysis

The following assessments are displayed in the order in which the tests were performed.

102

### Maximal voluntary contraction torque of the knee extensor muscles

Torque measurements on the right (dominant) leg were performed on an isokinetic dynamometer (System pro 4, Biodex Medical System, New York). The subject was seated on the dynamometer chair with a 90° hip angle. The knee joint axis was aligned with the dynamometer axis. The lever arm was attached 2 cm above the medial malleolus with a non-compliant strap. The maximal voluntary contraction (MVC) peak torque of the knee extensors was measured during isometric (MVC<sub>ISO</sub>) and concentric contractions. After a warm-up, DL performed two consecutive 5-s MVC<sub>ISO</sub>, separated by a 1-min rest period, with the right leg positioned at 70° of flexion (0°=fully extended). After a 1-min rest period, DL successively performed 2 concentric MVCs at 60°·s<sup>-1</sup> (MVC<sub>60</sub>) with a 95° range of motion (from 5° to 100° of knee flexion). A 1-min rest period was respected between trials. For each type of contraction (e.g. MVC<sub>iso</sub>), the peak torque of both trials was retained for analysis.

115

### Heart rate and gas exchange during maximal treadmill test

Because the subject was not familiar with treadmill running, a variable speed/grade procedure
was used. The test consisted of running at 7 km·h<sup>-1</sup> (0% slope) for 3 min, 8 km·h<sup>-1</sup> (0% slope)
for 3 min, and 9 km·h<sup>-1</sup> (0% slope) for 3 min. After the 9th min, speed was maintained at 9 km/h
but the slope was increased by 1% every minute until volitional exhaustion. The subject stopped
the test at the end of the 3% stage after 12 min of effort. Heart rate and respiratory gas exchange
parameters were recorded continuously during the test and maximal values were determined.

117

118

119

120

121

122
During the incremental treadmill test, heart rate was recorded every second using a heart rate monitor (Polar RS300; Polar Electro Oy, Kempele, Finland), and maximal heart rate (HRmax) was defined as the highest value recorded during the last 30 s of the test. Gas exchange during the test was collected using a breath-by-breath portable gas analyzer (Cosmed K4b², Rome, Italy). VO2max (ml·kg⁻¹·min⁻¹) and maximal carbon dioxide production (VCO2max, ml·kg⁻¹·min⁻¹) were both defined as the maximal value recorded over a 30-s period during the test. Maximal value of respiratory exchange ratio was determined as the highest ratio between the volumes of oxygen uptake and carbon dioxide production. Since O2 pulse during cardiopulmonary exercise testing has been associated with the onset of exercise-induced ischemia¹³, and is a powerful predictor of mortality in patients with cardiovascular disease,¹⁴ it was also calculated.

133

## Lower Limb MRI

Bilateral magnetic resonance imaging (MRI) scans of both lower limbs were performed using a 3.0 Tesla MRI scanner (Siemens Trio, Berlin, Germany) with the participant in supine lying, with knees and hips fully extended. Scanning parameters included: repetition time=723 ms; echo time=10 ms; α=140°; field of view=400x400 mm; pixel size=0.714 mm; width=560 pixels; Height=448 pixels; slice thickness=5 mm; slice increment 5 mm; number of slices=162.

Data were transferred in DICOM format.

For both legs, the triceps surae, tibialis anterior, quadriceps and other thigh muscles (OTM, including knee flexor and adductor muscles, and sartorius) were manually outlined for all the slices of the MRI images using 3D image analysis software (Mimics, Materialise, Belgium).

Examples of muscle area determination are presented in Fig.1A for the thigh muscles, and in Fig.1B for the calf muscles. The volume of each muscle or muscle group was calculated from 3D reconstruction (selected option on the mimic software: Optimal). A view of the 3D reconstruction is presented in Fig.1C.

148

## Bone mineral density (BMD)

BMD was assessed from dual energy X-ray absorptiometry scan (DXA) (Hologic Bone Densitometer system n°83752A, model Discovery A, Hologic Company, Marlborough, MA 01752, United States) for the left proximal femur region including the femoral neck, intertrochanteric region, greater trochanter.

154

## Statistical analysis

While chronological age is determined by date of birth, physiological age can vary according to numerous health metrics. In this study, we chose to compare some physiological characteristics (HRmax, VO2max, MVCISO, and MVC60) of DL by providing her estimated physiological age based on equations previously established in large samples. For HRmax, we used the equation (1) of Tanaka et al.¹⁵, obtained from a meta-analysis including 351 studies and 18,712 individuals. For VO2max, we used the equation (2) of Myers et al.¹⁶, obtained from a database including the VO2max (recorded during a maximal treadmill test) of 3,158 healthy females aged 20-79 years. For MVCISO, we used the equation (3) of Harbo et al.¹⁷, obtained from a database including the MVCISO of 85 females aged 21-75 years. For MVC60, we used the equation (4) of Neder et al.¹⁸, obtained from a database including the MVC60 of 51 females aged 20-80 years.

167

168

$$ (1) \text{Physiological age based on HRmax} = (208 - \text{HRmax}) / 0.7 $$

169

$$ (2) \text{Physiological age based on VO2max} = - (\text{VO2max} + 0.127 \times \text{weight}_{\text{ibs}}) - 66.2) / 0.39 $$

170

$$ (3) \text{Physiological age based on MVCISO} = - (\text{MVCISO} - 216 \times \text{height}_{\text{m}}) - 0.88 \times \text{weight}_{\text{kg}} + 201) / 0.96 $$

171

$$ (4) \text{Physiological age based on MVC60} = - (\text{MVC60} - 1.63 \times \text{weight}_{\text{kg}}) - \text{height}_{\text{m}} + 41.8) / 1.36 $$

172
For the total thigh, quadriceps and other thigh muscle volumes, data was normalized using Z-scores with individual data expressed as the number of standard deviations from the mean of the 'healthy older females' group in the study by Maden-Wilkinson et al.,¹⁹ calculated as:

176

177

178

where $\chi$ is the value for DL, and $\mu$ and $\sigma$ are the mean and standard deviation respectively, of the older female sample. While reports of triceps surae muscle volume in older females are rare, Z-scores were obtained from the study by Csapo et al.,²⁰ which measured triceps surae volume in five healthy Japanese females aged ~83 years.

To determine whether DL had a risk of bone fracture despite her high physical activity level, T-scores of BMD were used to compare DL with healthy young females with peak bone mass according to the manufacturer's instructions and the World Health Organization.²¹ A T-score between +1 and -1 denotes normal bone density. A T-score between -1 and -2.5 indicates low bone density or osteopenia. A T-score of -2.5 or lower reveals the presence of osteoporosis. Z-scores for BMD, providing a comparison with the bone density of people of the same age and sex as the patient, were also obtained. A negative Z-score of -2.5 or less should raise concern about a secondary cause of osteoporosis.

191

$$Z\text{-score} = (\chi - \mu) / \sigma$$

<figure><img src="image_1.png" /></figure>

192

193

<caption>**Figure 1: Muscle segmentation of right (dominant) leg and volume reconstruction of muscles and bones of both legs of the subject.**</caption>

A presents a magnetic resonance image at the mid-point of the femur of the right leg. B presents a magnetic resonance image in the first third of the tibia of the right leg. C represents the 3D reconstruction of muscle and bone volumes of both legs. Q: quadriceps; OTM: other thigh muscles; TS: triceps surae.
## 200 RESULTS

As displayed in Table 1, DL had an exceptional VO2max (42.3 ml·kg⁻¹·min⁻¹) and normal muscle strength for her age. Her lower limb muscle volumes were just slightly better than expected for her age (Table 2). The bone mineral density was 0.739 g·cm⁻² (T-score: -0.8; Z-score: 1.5) for the femoral neck, 0.523 g·cm⁻² (T-score: -1.9; Z-score: -0.3) for the greater trochanter, 0.986 g·cm⁻² (T-score: -0.8; Z-score: 1.6) for the intertrochanteric region and 0.745 g·cm⁻² (T-score: -1.7; Z-score: 0.7) for the total of the left proximal femur region.

## 208 DISCUSSION

This single case study reported, for the first time, some physiological characteristics of a high-level female master runner aged over 80 years.

During the maximal treadmill test, DL had a respiratory exchange ratio at VO2max just below 1, indicating a possible underestimation of her true VO2max. Despite this, DL presented, to the best of our knowledge, the highest value of VO2max ever observed for an octogenarian female. On the basis of her VO2max, we showed that she had a physiological age of ~27 years. Her VO2max was slightly higher than in young females (~30-35 ml·kg⁻¹·min⁻¹)⁴ and 60-to-69-year-old endurance-trained females (~38.0 ml·kg⁻¹·min⁻¹),⁷ but considerably above the mean values in females aged 70-to-79-year-old (~16-21 ml·kg⁻¹·min⁻¹).⁴ While DL had a low body mass compared to the populations of young and elderly females, her absolute VO2max (1.99 l·min⁻¹) was twice that of females aged 70-to-79-year-old (VO2max: 1.05 l·min⁻¹) and comparable to that of young females (20-25 years, VO2max: 2.04 l·min⁻¹).⁴ It can be assumed that DL had some hereditary advantages for cardiorespiratory fitness, VO2max and its trainability being related to genetic predisposition.²² However, age-related decline in VO2max could have been prevented, due to her participation in a training program for competitive running performance of distances up to 10km, from the age of 69 years. Indeed, it is well known that older persons can minimize the reduction in age-related VO2max, if they maintain high levels of physical activity.²³ In addition to her past and actual training program, DL's level of physical training is evidenced by her very low body fat content (~15%) in comparison to reference values in elderly females (~40%).²⁴ DL's physiological age for HRmax (~74 years) was slightly lower than her biological age (83 years). The high VO2max and HRmax level explained the high value of O₂ pulse, corresponding to the mean values reported in a population in the 5th decade.²⁵ It is worth noting that O₂ pulse increased almost linearly during the treadmill test, indicating an absence of cardiac ischemia.¹³ These observations attest the extremely well-preserved cardiovascular and respiratory fitness of this master female athlete.

As shown by the T-scores and Z-scores for BMD, DL did not suffer from sarcopenia. However, her muscle characteristics seemed to be similar or only slightly better than those generally observed for her age and sex. DL's physiological age based on isokinetic strength (83 years) was fairly similar to her biological age (83 years), but it was higher when based on her maximal isometric strength (90 years). It is worth noting that the equation used to calculate DL's physiological age only included females aged from 21 to 75 years, which may have led to an overestimation of her physiological age. Indeed, an accelerated decline in physical performance has been observed after approximately 80 years, suggesting that physiological functions decline rapidly at around 80 years.²⁶ The study of DL's leg muscle volumes confirmed a potential overestimation of her physiological age. Her thigh muscle volumes were fairly comparable with those of older females aged ~72 years,¹⁹ showing that DL's muscle quantity was well-preserved for her age. This preservation was more noticeable for the triceps surae, as it was 22% greater than that of five Japanese females in the same age range.²⁰ Our observations regarding DL's muscle function are in line with a recent meta-analysis⁹ in male master athletes competing in endurance events, which showed that, in contrast to master strength/power athletes, chronic
250 endurance exercises did not prevent the loss of muscular strength. Chronic endurance training
251 therefore does not seem to prevent the age-related decline in muscular strength for either males
252 or females.

253
254 DL's BMD for the proximal femur region was within the osteopenia range, only revealing an
255 increased fracture risk. Therefore, DL did not have osteoporosis, despite the early menopause
256 and relatively low calcium intake, probably due to the regular training conducted over the
257 minimum effective amount shown to positively affect BMD [2.5 exercise sessions/week].²⁷
258 However, the Z-scores at the proximal femur region (0.7) showed that DL's BMD was clearly
259 similar to that of females of the same age. This result confirms that post-menopausal female
260 master runners do not seem to benefit from specific bone protection.¹²

261
262 CONCLUSION
263 The present single case study of a master female runner shows that remarkable cardiorespiratory
264 fitness, associated with long-term endurance training, is not associated with a specific
265 preservation of muscle and skeletal characteristics.

266
267 PRACTICAL APPLICATIONS
268 The results of this study do not support the use of highly intensive aerobic training to prevent
269 age-related declines in muscle strength and bone quality in females.

270
271 CONFLICTS OF INTEREST
272 All authors declare no conflicts of interest.

273
274 REFERENCES
275

276 1. Tanaka H, Seals DR. Endurance exercise performance in Masters athletes: age-associated changes and underlying physiological mechanisms. *J Physiol*. 2008;586(1):55-63. doi:10.1113/jphysiol.2007.141879

277 2. Webb JL, Urner SC, McDaniels J. Physiological Characteristics of a Champion Runner: Age 77. *J Gerontol*. 1977;32(3):286-290. doi:10.1093/geronj/32.3.286

279 3. Trappe S, Hayes E, Galpin A, et al. New records in aerobic power among octogenarian lifelong endurance athletes. *J Appl Physiol*. 2013;114(1):3-10. doi:10.1152/japplphysiol.01107.2012

281 4. Kaminsky LA, Imboden MT, Arena R, Myers J. Reference Standards for Cardiorespiratory Fitness Measured With Cardiopulmonary Exercise Testing Using Cycle Ergometry: Data From the Fitness Registry and the Importance of Exercise National Database (FRIEND) Registry. *Mayo Clin Proc*. 2017;92(2):228-233. doi:10.1016/j.mayocp.2016.10.003

285 5. Karlsen T, Leinan IM, Bækkerud FH, et al. How to Be 80 Year Old and Have a VO₂max of a 35 Year Old. *Case Rep Med*. 2015;2015:1-6. doi:10.1155/2015/909561

287 6. Lepers R, Stapley PJ, Cattagni T, Gremeaux V, Knechtle B. Limits in endurance performance of octogenarian athletes. *J Appl Physiol*. 2013;114(6):829. doi:10.1152/japplphysiol.00038.2013

289 7. Wiswell RA, Jaque S V, Marcell TJ, et al. Maximal aerobic power, lactate threshold, and running performance in master athletes. *Med Sci Sports Exerc*. 2000;32(6):1165-1170. doi:10.1097/00005768-200006000-00021

292 8. Vaitkevicius P V, Fleg JL, Engel JH, et al. Effects of age and aerobic capacity on arterial stiffness in healthy adults. *Circulation*. 1993;88(4 Pt 1):1456-1462. http://www.ncbi.nlm.nih.gov/pubmed/8403292. Accessed July 3, 2018.

295 9. Mckendry J, Breen L, Shad BJ, Greig CA. Muscle morphology and performance in master athletes: A systematic review and meta-analyses. *Ageing Res Rev*. 2018;45:62-82. doi:10.1016/j.arr.2018.04.007

297 10. Hansen M, Kjaer M. Influence of Sex and Estrogen on Musculotendinous Protein Turnover at Rest and After Exercise. *Exerc Sport Sci Rev*. 2014;42(4):183-192. doi:10.1249/JES.0000000000000026

299 11. Wiswell RA, Hawkins SA, Dreyer HC, Jaque S V. Maintenance of BMD in Older Male Runners Is Independent of Changes in Training Volume or VO2peak. *Journals Gerontol Ser A Biol Sci Med Sci*. 2002;57(4):M203-M208. doi:10.1093/gerona/57.4.M203

302 12. Hawkins SA, Wiswell RA, Jaque S V, et al. The inability of hormone replacement therapy or chronic running to maintain bone mass in master athletes. *J Gerontol A Biol Sci Med Sci*. 1999;54(9):M451-5.
304 http://www.ncbi.nlm.nih.gov/pubmed/10536648. Accessed July 20, 2018.
305 13. Belardinelli R, Lacalaprice F, Carle F, et al. Exercise-induced myocardial ischaemia detected by cardiopulmonary exercise testing. *Eur Heart J.* 2003;24(14):1304-1313.
306 http://www.ncbi.nlm.nih.gov/pubmed/12871687. Accessed September 14, 2018.
307
308 14. Oliveira RB, Myers J, Araújo CGS, Abella J, Mandic S, Froelicher V. Maximal exercise oxygen pulse as a predictor of mortality among male veterans referred for exercise testing. *Eur J Cardiovasc Prev Rehabil.* 2009;16(3):358-364. doi:10.1097/HJR.0b013e3283292fe8
309
310
311 15. Tanaka H, Monahan KD, Seals DR. Age-predicted maximal heart rate revisited. *J Am Coll Cardiol.* 2001;37(1):153-156. http://www.ncbi.nlm.nih.gov/pubmed/11153730. Accessed September 7, 2018.
312
313 16. Myers J, Kaminsky LA, Lima R, Christle JW, Ashley E, Arena R. A Reference Equation for Normal Standards for VO2 Max: Analysis from the Fitness Registry and the Importance of Exercise National Database (FRIEND Registry). *Prog Cardiovasc Dis.* 2017;60(1):21-29.
315
316 doi:10.1016/J.PCAD.2017.03.002
317 17. Harbo T, Brincks J, Andersen H. Maximal isokinetic and isometric muscle strength of major muscle groups related to age, body mass, height, and sex in 178 healthy subjects. *Eur J Appl Physiol.* 2012;112(1):267-275. doi:10.1007/s00421-011-1975-3
318
319
320 18. Neder JA, Nery LE, Shinzato GT, Andrade MS, Peres C, Silva AC. Reference Values for Concentric Knee Isokinetic Strength and Power in Nonathletic Men and Women from 20 to 80 Years Old. *J Orthop Sport Phys Ther.* 1999;29(2):116-126. doi:10.2519/jospt.1999.29.2.116
321
322
323 19. Maden-Wilkinson TM, McPhee JS, Rittweger J, Jones DA, Degens H. Thigh muscle volume in relation to age, sex and femur volume. *Age (Dordr).* 2014;36(1):383-393. doi:10.1007/s11357-013-9571-6
324
325 20. Csapo R, Malis V, Sinha U, Du J, Sinha S. Age-associated differences in triceps surae muscle composition and strength – an MRI-based cross-sectional comparison of contractile, adipose and connective tissue. *BMC Musculoskelet Disord.* 2014;15(1):209. doi:10.1186/1471-2474-15-209
326
327
328 21. Kanis JA, McCloskey E V., Johansson H, Oden A, Melton LJ, Khaltaev N. A reference standard for the description of osteoporosis. *Bone.* 2008;42(3):467-475. doi:10.1016/j.bone.2007.11.001
329
330 22. Williams CJ, Williams MG, Eynon N, et al. Genes to predict VO2max trainability: a systematic review. *BMC Genomics.* 2017;18(Suppl 8):831. doi:10.1186/s12864-017-4192-6
331
332 23. Hagberg J. Effect of training on the decline of VO2max with aging. *Fed Proc.* 1987;46(5):1830-1833.
333 https://europepmc.org/abstract/med/3556603. Accessed March 19, 2019.
334 24. Pedersen AN, Ovesen L, Schroll M, Avlund K, Era P. Body composition of 80-years old men and women and its relation to muscle strength, physical activity and functional ability. *J Nutr Health Aging.* 2002;6(6):413-420. http://www.ncbi.nlm.nih.gov/pubmed/12459892. Accessed March 19, 2019.
335
336
337 25. Oliveira RB, Myers J, Araújo CGS de. Long-term stability of the oxygen pulse curve during maximal exercise. *Clinics (Sao Paulo).* 2011;66(2):203-209. doi:10.1590/S1807-59322011000200004
338
339 26. Knechtle B, Kohler G, Rosemann T. Study of a European male champion in 10-km road races in the age group &gt;85 years. *Proc (Bayl Univ Med Cent).* 2010;23(3):259-260.
340
341 http://www.ncbi.nlm.nih.gov/pubmed/20671823. Accessed September 14, 2018.
342 27. Kemmler W, von Stengel S, Kohl M. Exercise Frequency and Fracture Risk in Older Adults—How Often Is Enough? *Curr Osteoporos Rep.* 2017;15(6):564-570. doi:10.1007/s11914-017-0407-7
343
344
345