You lose muscle as you get older – but only if you don’t do anything about it

From the fifth decade of life onwards, we lose muscle mass [1] and gain fatty tissue around our stomachs [2]. This is very detrimental to our health as it can lead to sarcopenia (age-associated muscle loss) frailty, falls and metabolic diseases.

But is it really just age that causes us to lose strength and muscle mass? Do people who exercise all their lives lose strength and muscle mass, and, if so, how much? How does their body composition change over time? These are questions that a research team in Finland and China investigated [3]. They examined young (20-39 years, n = 109) and old (70-89 years, n = 147) male competitive athletes and 147 healthy control subjects of the same age (young = 53, older = 94 males).

They divided the athletes into different groups corresponding to three different trained disciplines. A strength group (weightlifters and power lifters), a sprint group (sprinters and long jumpers) and an endurance sports group (long-distance runners and cross-country skiers). Body composition was measured using dual x-ray absorptiometry (DXA). The team of scientists measured the lean mass of all limbs and combined them, then compared them against the clinically established thresholds for low muscle mass, obesity and sarcopenic obesity to analyse the occurrence in each group.

Regular exercise protects muscle mass

The DXA results showed that young strength athletes have significantly more muscle mass in their arms and legs than their peers in the control group (P < 0.001). This also applies to the comparison of young sprint athletes with participants of the same age in the control group (P < 0.001). Muscle mass in young endurance athletes didn’t differ from that of their peers in the control group. Young sprint athletes also had more muscle mass than young endurance athletes (P < 0.001).

In older people, it was found that sprint athletes also had more muscle mass than their peers in the control group (P < 0.001). However, in contrast to young endurance athletes, older endurance athletes have significantly more muscle mass than participants of the same age in the control group (P < 0.05).

People with muscle mass in their extremities below the limit of 20 kg [4] came mainly from the older control group and accounted for 16% of participants. In the athlete groups, only two older endurance athletes (3%) and one strength athlete (2%) were below this limit.

Fat mass

Sprint and endurance athletes had less fat mass compared to their control groups (P < 0.001) regardless of age. These athletes also had lower fat mass compared to the strength group (P < 0.001). According to the Obesity Medicine Association [5], the threshold for obesity is a fat percentage of > 25%. Nineteen people from the young control group and 68 people from the older control group exceeded this value. Only seven of the strength athletes were in the young age group, with 24 in the older age group. Among the sprint and endurance athletes, there was one person in the young age group and three in the older age group.

Sarcopenic obesity

Across the young groups, only one person – from the control group – had less than 20 kg of muscle mass and more than 25% fat mass. In the older group, there were two endurance athletes, one strength athlete and 18 control subjects.

In contrast to endurance athletes and the control group, strength athletes have more muscle mass, while fat mass was not significantly different in the strength athletes compared to the control group (P > 0.05). However, endurance and sprint athletes had lower fat mass than the control participants (P < 0.05). The prevalence of low muscle mass below the threshold, obesity and sarcopenic obesity was highest in the older control group.

Age isn’t to blame

Another study by an international research group examined the muscle composition of sprint athletes [6]. They compared muscle biopsies in 2002 with muscle biopsies from the same sprinters 10 years later. In 2002, the average training time per week was 6.8 ± 3.1 h and decreased slightly to 4.4 ± 2.4 h 10 years later. Age also had an influence on the 60 m sprint time, which was almost 12% slower in 2012. Although age led to a loss of around 1 cm in height, the muscles showed no significant changes. No muscle atrophy was noted, despite the fact that average training time decreased.

Sport and/or strength training protects and maintains muscles. So, it’s not age, per se, but the sluggishness and inactivity associated with age that primarily contribute to the loss of muscle mass and strength. So, it’s worth taking care of your muscles. That’s what lets you interact with your environment and do the things you love, be it jogging, weight training, skiing, climbing, mountain biking, etc.

I call this period of time based on the health span the performance span. It’s the time that you can actively spend doing the activities you love. It’s important that exercise and especially strength training are part of everyday life, just like brushing your teeth. It’s never too late to start, and it’s never a bad idea to invest time in something that will pay off as you get older.

References

1. Mitchell WK, Williams J, Atherton P, Larvin M, Lund J, Narici M. Sarcopenia, dynapenia, and the impact of advancing age on human skeletal muscle size and strength; a quantitative review. Front Physiol. Frontiers; 2012;3 JUL: 260. doi:10.3389/FPHYS.2012.00260/BIBTEX
2. Tchkonia T, Morbeck DE, Von Zglinicki T, Van Deursen J, Lustgarten J, Scrable H, et al. Fat tissue, aging, and cellular senescence. Aging Cell. John Wiley & Sons, Ltd; 2010;9: 667–684. doi:10.1111/J.1474-9726.2010.00608.X
3. Walker S, von Bonsdorff M, Cheng S, Häkkinen K, Bondarev D, Heinonen A, et al. Body composition in male lifelong trained strength, sprint and endurance athletes and healthy age-matched controls. Front Sport Act Living. Frontiers; 2023;5: 1295906. doi:10.3389/FSPOR.2023.1295906
4. Cruz-Jentoft AJ, Bahat G, Bauer J, Boirie Y, Bruyère O, Cederholm T, et al. Sarcopenia: Revised European consensus on definition and diagnosis [Internet]. Age and Ageing. Oxford University Press; 2019. pp. 16–31. doi:10.1093/ageing/afy169
5. Shah NR, Braverman ER. Measuring Adiposity in Patients: The Utility of Body Mass Index (BMI), Percent Body Fat, and Leptin. PLoS One. Public Library of Science; 2012;7:e33308. doi:10.1371/JOURNAL.PONE.0033308
6. Messa GAM, Korhonen MT, Degens H. No ageing-related increase in fibre type grouping in sprint-trained masters runners: A 10-year follow-up study. J Cachexia Sarcopenia Muscle. Springer Nature; 2024; doi:10.1002/JCSM.13416