In a recent short term paper published in the journal BMJ Open Sport & Exercise Medicine, Researchers investigated the long-term effects of varying intensities of supervised resistance training in retirement-age adults.
The study findings highlight that participants in the high resistance training (HRT) cohort maintained muscle performance, particularly in their leg isometric strength. In contrast, the muscles of participants in the moderate-intensity training group (MIT) and the no-exercise control group (CON) were observed to significantly decline in strength (and, by extension, function) three years after the end of the supervised baseline study training.
Record
Modern medical advances have significantly extended human life worldwide. An unintended consequence of this otherwise positive progress is an increase in age-related chronic health conditions (e.g. cardiovascular disease [CVD] and cancers) and loss of autonomy in older people.
Recent research has suggested that while the normal aging process contributes to skeletal muscle declines and, in turn, autonomic losses, resistance training may help maintain muscle strength, thereby reducing suboptimal outcomes. Unfortunately, most studies on the subject are short-term, with a significant absence of data on the long-term benefits of supervised muscle training in people over retirement age.
The Live Active Successful Aging (LISA) study was a large cohort, randomized controlled trial conducted in 2020 in 451 participants of retirement age (~64-75 years, mean age at study entry was 67). Study age, sex, body mass index (BMI) and chair rise test performance (leg strength and endurance test) matched participants into three groups – high resistance training (HRT, n = 149) , moderate-intensity training (MIT; n = 154) and no-exercise controls (CON; n = 148) to elucidate the long-term effects of resistance training at different intensities.
Interventions in the training cohorts were supervised and machine-based, involving three full-body sessions per week over one year. The Brzycki prediction equation was used to determine training intensity in HRT (3 sets of 6–12 repetitions at ~70%–85% of 1 repetition maximum [RM]) and MIT (3 sets of 10–18 repetitions at ~50%–60% of 1RM).
Initial study findings and those at the first round of long-term follow-up (one year) revealed that while the HRT cohort maintained skeletal muscle strength and function, these variables were significantly reduced in participants in the MIT and CON cohorts. This suggests that exercise alone may be insufficient to maintain optimal muscle function. Exercise intensity may be necessary to achieve desired results.
About the study
This interim report is part of the long-term follow-up with LISA participants and is being conducted four years after the original study. Additional exhibitions are planned three and six years after this one.
The present study included 369 of the original 451, with the remaining 82 adults dropping out due to lack of motivation or serious ongoing illness. The study cohort has a mean age of 71 years and 61% are women. Data collection of the study took place over three days. It included a complete health check (Day 1), dual-energy X-ray absorptiometry (DXA), visceral fat mass assessment, isometric leg strength assessment (Day 2), and brain and thigh magnetic resonance imaging (MRI) (Day 3). ).
In addition, daily step count was measured using an accelerometer as a proxy for daily physical activity among participants. Statistical analyzes were performed between cohorts using paired Student’s t-tests (to assess changes from baseline) and two-way mixed-model analyzes of variance (ANOVAs) to elucidate between-group differences. Models were controlled for gender and age, and Bonferroni corrections were applied to multiple comparisons.
Study findings
Dropouts, particularly those who withdrew due to lack of motivation, were observed to have a higher mean body weight, BMI, and waist circumference at baseline than participants who persisted through the fourth year of follow-up. Notably, the results of resistance training in participants and dropouts (measured at the previous one-year follow-up) were not statistically different.
Encouragingly, daily physical activity assessments of study participants revealed that, despite advancing age (mean = 71), participants remained active, on average nearly meeting the optimal threshold of 10,000 steps recommended by scientists and clinicians doctors for people half their age. Baseline-to-present comparisons revealed that while significant decreases in leg isometric strength were observed in the MIT and CON cohorts, strength was maintained at approximately baseline values in the HRT participants, meaning there were no losses in function despite four years of additional aging .
Overall muscle strength was observed to follow similar trends – while the MIT and CON cohorts showed significant losses compared to baseline measurements, the HRT cohort gained muscle strength compared to baseline (pre-intervention) values. Notably, all three cohorts were observed to have experienced reductions in lean leg mass.
These results suggest that the HRT cohort gained muscle function despite muscle loss. Additional research is needed to elucidate the mechanisms (neural or physical) that underpin these findings.
Estimates of lean body mass and visceral fat were observed to be optimal in HRT participants (decreases), while MIT (no change) and CONS (significant increases) subjects showed suboptimal time*group results over the four years from baseline evaluations. Handgrip strength and leg extension strength, currently accepted measures of muscle function, showed time-related declines in all cohorts.
Surprisingly, while between-cohort functional differences were statistically significant (HRT > MIT > CONS), within-cohort deltas (Change) did not change over the four-year follow-up. The authors hypothesize that this may be due to the data set including participants who are substantially more active than the average 71-year-old, although additional research is needed to clarify this observation.
conclusion
In summary, these findings highlight the role of training intensity in long-term muscle strength and maintenance of function. These findings come with caveats – while the HRT group depicted significantly improved retention of leg strength compared to the MIT and CON cohorts, handgrip strength, the currently accepted measure of overall muscle strength, did not differ between groups.
“Notably, benefits in leg strength were present despite reduced leg lean mass. Neural adaptations influence the response to resistance training. The present results suggest that these adaptations may play a role even when leg lean mass is reduced.” legs and the CSA of the thighs.”
These findings highlight that a period of high-intensity resistance training can have sustained muscle strength and functional benefits in older adults for four or more years, whereas lower-intensity training programs do not share these benefits.
