Preserved Capacity for Adaptations in Strength and Muscle Regulatory Factors in Elderly in Response to Resistance Exercise Training and Deconditioning.

Andreas Mæchel Fritzen,Thomas Krag,Khaled Abdul Nasser Qadri,Tina D Jeppesen,John Vissing,Marie-Louise Sveen,Frank D Thøgersen

doi:10.3390/jcm9072188

Andreas Mæchel Fritzen, Thomas Krag + Show 5 more

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https://doi.org/10.3390/jcm9072188

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Abstract

Aging is related to an inevitable loss of muscle mass and strength. The mechanisms behind age-related loss of muscle tissue are not fully understood but may, among other things, be induced by age-related differences in myogenic regulatory factors. Resistance exercise training and deconditioning offers a model to investigate differences in myogenic regulatory factors that may be important for age-related loss of muscle mass and strength. Nine elderly (82 ± 7 years old) and nine young, healthy persons (22 ± 2 years old) participated in the study. Exercise consisted of six weeks of resistance training of the quadriceps muscle followed by eight weeks of deconditioning. Muscle biopsy samples before and after training and during the deconditioning period were analyzed for MyoD, myogenin, insulin-like growth-factor I receptor, activin receptor IIB, smad2, porin, and citrate synthase. Muscle strength improved with resistance training by 78% (95.0 ± 22.0 kg) in the elderly to a similar extent as in the young participants (83.5%; 178.2 ± 44.2 kg) and returned to baseline in both groups after eight weeks of deconditioning. No difference was seen in expression of muscle regulatory factors between elderly and young in response to exercise training and deconditioning. In conclusion, the capacity to gain muscle strength with resistance exercise training in elderly was not impaired, highlighting this as a potent tool to combat age-related loss of muscle function, possibly due to preserved regulation of myogenic factors in elderly compared with young muscle.

Highlights

Six weeks of resistance exercise training increased quadriceps muscle strength in the elderly group by 78% (53.4 ± 14.3 kg vs. 95.0 ± 22.0 kg; p < 0.05), which was similar to that found in the young healthy persons (83.5%; 97.1 ± 27.5 kg vs. 178.2 ± 44.2 kg; p < 0.05) (Figure 2A)
Pre-exercise, the elderly men did not have a significantly greater muscle strength compared to elderly women (56.2 ± 16.1 kg vs. 46.5 ± 2.5 kg), whereas a gender difference in muscle strength was observed in the younger group, in which the younger men had a 59% greater muscle strength at pre-training compared to younger women (119.2 ± 19.5 kg vs. 75 ± 12.6 kg; p < 0.05) (Figure 2A)
The present study suggests that the myogenic program is intact in the elderly, as the levels of MyoD, myogenin, and insulin-like growth factor-I (IGF-I)-R are activated to the same extent as in younger skeletal muscle

Summary

Introduction

6–10 weeks of exercise training increased skeletal muscle strength to a similar extent in young and elderly in some studies [4,5], others report greater improvements in young individuals [6,7]. It is of key interest to elucidate whether increased muscle strength after a period of resistance exercise training occurs to a similar or blunted extent in old compared to young muscle. An aged-associated loss of muscle mass or strength [10,11] appears improved with resistance training in elderly individuals [12,13,14,15,16], several studies find a blunted muscle hypertrophy response [17,18,19]

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