Maintenance of muscle strength following a one-year resistance training program in older adults.

BACKGROUND: Muscle mass, strength and function declines with advancing age. Strength training (ST) improves these parameters in older adults, but the gains often disappear after completion of a short-term intervention. The purpose of the present study was to investigate muscle mass, -strength and -function one year after the completion of a successful long-term (12 months) supervised ST program in older adults. METHOD: Men and women (n = 419, age: 62-70 years) completed one year of supervised heavy resistance training (HRT, n = 143) or moderate intensity resistance training (MIT, n = 144) and were compared to a non-exercising control group (CON, n = 132). At 1-year follow-up, 398 participants returned for measurements of muscle power, -strength and -mass, physical function, body composition, hippocampus volume and physical/mental well-being. The results were compared to pre-training (baseline) and post-training (1-year) values. Further, the participants from the two previous training groups (HRT + MIT, n = 265) were divided into 1) those who on their own continued the ST program (>9 months) the year after completion of the supervised ST program (CONTIN, n = 65) and 2) those who stopped during the follow-up year (<9 months) (STOP, n = 200). RESULTS: Out of all the improvements obtained after the 1-year training intervention, only knee extensor muscle strength in HRT was preserved at 1-year follow-up (p < 0.0001), where muscle strength was 7% higher than baseline. Additionally, the decrease in muscle strength over the second year was lower in CONTIN than in STOP with decreases of 1% and 6%, respectively (p < 0.05). Only in CONTIN was the muscle strength still higher at 1-year follow-up compared with baseline with a 14% increase (p < 0.0001). The heavy strength training induced increase in whole-body lean mass was erased at 1-year follow-up. However, there was a tendency for maintenance of the cross-sectional area of m. vastus lateralis from baseline to 1-year follow-up in HRT compared with CON (p = 0.06). Waist circumference decreased further over the second year in CONTIN, whereas it increased in STOP (p < 0.05). CONCLUSION: Even though long-term strength training effectively improved muscle function and other health parameters in older adults, only knee extensor muscle strength was preserved one year after completion of heavy (but not moderate intensity) resistance training. Continuation of strength training resulted in better maintenance of muscle strength and health, which indicates that it is required to continue with physical activity to benefit from the long-term effects of strength training upon muscle function and health in older men and women.

The influence of prolonged strength training upon muscle and fat in healthy and chronically diseased older adults.

BACKGROUND: Physical muscle function and brain hippocampus size declines with age, accelerating after the age of 60. Strength training over a few months improves physical function, but less is known about how long-term strength training affects physical function and hippocampus volume. Therefore, we aimed to investigate the effect of 1-year strength training of two different intensities upon muscle mass, function, and hippocampus volume in retirement-age individuals. METHODS: In this multidisciplinary randomized controlled trial (clinicaltrials.gov: NCT02123641), participants were allocated to either a) supervised, heavy resistance training (HRT, n = 149, 3/wk), b) moderate intensity resistance training (MIT, n = 154, 3/wk) or c) non-exercise activities (CON, n = 148). 451 participants were randomized (62-70 yrs., women 61%, ≈80% with a chronic medical disease) and 419 were included in the intention-to-treat analysis (n = 143, 144 and 132; HRT, MIT and CON). Changes in muscle power (primary outcome), strength and size, physical function, body composition, hippocampus volume and physical/mental well-being were analyzed. FINDINGS: Of the participants (HRT + MIT), 83% completed training at least 2/week. Leg extensor power was unchanged in all groups, but strength training had a positive effect on isometric knee extensor strength in both groups, whereas an increased muscle mass, cross-sectional area of vastus lateralis muscle, a decreased whole-body fat percentage, visceral fat content and an improved mental health (SF-36) occurred in HRT only. Further, chair-stand performance improved in all groups, whereas hippocampus volume decreased in all groups over time with no influence of strength training. INTERPRETATION: Together, the results indicate that leg extensor power did not respond to long-term supervised strength training, but this type of training in a mixed group of healthy and chronically diseased elderly individuals can be implemented with good compliance and induces consistent changes in physiological parameters of muscle strength, muscle mass and abdominal fat.

Physical activity as intervention for age-related loss of muscle mass and function: protocol for a randomised controlled trial (the LISA study).

INTRODUCTION: Physical and cognitive function decline with age, accelerating during the 6th decade. Loss of muscle power (force×velocity product) is a dominant physical determinant for loss of functional ability, especially if the lower extremities are affected. Muscle strength training is known to maintain or even improve muscle power as well as physical function in older adults, but the optimal type of training for beneficial long-term training effects over several years is unknown. Moreover, the impact of muscle strength training on cognitive function and brain structure remains speculative. The primary aim of this randomised controlled trial is to compare the efficacy of two different 1 year strength training regimens on immediate and long-lasting improvements in muscle power in retirement-age individuals. Secondary aims are to evaluate the effect on muscle strength, muscle mass, physical and cognitive function, mental well-being, health-related quality of life and brain morphology. METHODS AND ANALYSIS: The study includes 450 home-dwelling men and women (62-70 years). Participants are randomly allocated to (1) 1 year of supervised, centre-based heavy resistance training, (2) home-based moderate intensity resistance training or (3) habitual physical activity (control). Changes in primary (leg extensor power) and secondary outcomes are analysed according to the intention to treat principle and per protocol at 1, 2, 4, 7 and 10 years. ETHICS AND DISSEMINATION: The study is expected to generate new insights into training-induced promotion of functional ability and independency after retirement and will help to formulate national recommendations regarding physical activity schemes for the growing population of older individuals in western societies. Results will be published in scientific peer-reviewed journals, in PhD theses and at public meetings. The study is approved by the Regional Ethical Committee (Capital Region, Copenhagen, Denmark, number H-3-2014-017). TRIAL REGISTRATION NUMBER: NCT02123641.