Strength training increases skeletal muscle quality but not muscle mass in old institutionalized adults: a randomized, multi-arm parallel and controlled intervention study.

BACKGROUND: Age related loss of skeletal muscle mass is accompanied by changes in muscle quality leading to impairment of functional status.

AIM: This study investigated the effect of resistance training and nutritional supply on muscle mass and muscle quality in very old institutionalized adults.

DESIGN: Prospective, randomized, multi-arm parallel and controlled intervention study.

SETTING: This study was conducted in five retirement care facilities.

POPULATION: This subgroup of the Vienna Active Ageing Study included 54 women and men (82.4±6.0 years) with impaired health status. Participants were randomly assigned either to elastic band resistance training (N.=16), training with nutritional supplementation (N.=21) or control group (N.=17).

METHODS: Health status was assessed at baseline with functional tests, cognitive status, nutritional status, sum of medications as well as sum of diseases. Skeletal muscle mass, determined by dual-energy X-ray absorptiometry, isokinetic knee extension and flexion force and handgrip strength were assessed at baseline and after 6 months. Muscle quality of lower extremities was defined as ratio of the extensor (MQ_LE (Ext.)) or flexor strength (MQ_LE (Flex.)) to lean leg mass. Muscle quality of upper extremity was defined as ratio of handgrip strength to lean arm mass. Follow-up examinations were performed after 12 and 18 months of intervention.

RESULTS: Muscle quality, but not muscle mass, showed significant correlations to functional tests at baseline (0.300 - 0.614, P<0.05). Resistance training significantly enhanced muscle quality of lower extremity after 6 months (MQ_LE (Ext.) +19.8%, MQ_LE (Flex.) +30.8%, P<0.05). Nutritional supplementation could not further increase the training effect. Participants with lower muscle quality at baseline benefit most from the training intervention. Skeletal muscle mass was not changed by any intervention.

CONCLUSIONS: Resistance training with elastic bands improved muscle quality in very old people. Additional nutritional supplementation was not able to further improve the effects obtained by training alone.

CLINICAL REHABILITATION IMPACT: Elastic band resistance training could be safely used to improve muscle quality even in old people with impaired health status. Weak and chronically ill participants benefit most from this training.