Training-induced changes in muscle CSA, muscle strength, EMG, and rate of force development in elderly subjects after long-term unilateral disuse

Abstract

The ability to develop muscle force rapidly may be a very important factor to prevent a fall and to perform other tasks of daily life. However, information is still lacking on the range of training-induced neuromuscular adaptations in elderly humans recovering from a period of disuse. Therefore, the present study examined the effect of three types of training regimes after unilateral prolonged disuse and subsequent hip-replacement surgery on maximal muscle strength, rapid muscle force [rate of force development (RFD)], muscle activation, and muscle size. Thirty-six subjects (60-86 yr) were randomized to a 12-wk rehabilitation program consisting of either 1) strength training (3 times/wk for 12 wk), 2) electrical muscle stimulation (1 h/day for 12 wk), or 3) standard rehabilitation (1 h/day for 12 wk). The nonoperated side did not receive any intervention and thereby served as a within-subject control. Thirty subjects completed the trial. In the strength-training group, significant increases were observed in maximal isometric muscle strength (24%, P < 0.01), contractile RFD (26-45%, P < 0.05), and contractile impulse (27-32%, P < 0.05). No significant changes were seen in the two other training groups or in the nontrained legs of all three groups. Mean electromyogram signal amplitude of vastus lateralis was larger in the strength-training than in the standard-rehabilitation group at 5 and 12 wk (P < 0.05). In contrast to traditional physiotherapy and electrical stimulation, strength training increased muscle mass, maximal isometric strength, RFD, and muscle activation in elderly men and women recovering from long-term muscle disuse and subsequent hip surgery. The improvement in both muscle mass and neural function is likely to have important functional implications for elderly individuals.

Rehabilitation following total hip arthroplasty evaluation over short follow-up time: Randomized clinical trial

“…The decision to examine a short follow-up period resulted from our conclusion that no previous study has shown the efficacy of a rehabilitation protocol in a very short follow-up period of 15 d postsurgery. Most of the previous studies [13,[26][27][28] made assessments over periods of 4,8,12, and 16 wk.…”

“…The current study demonstrated significant positive results in the improvement of muscle strength force in the intervention group compared with the nonintervention group, and these findings were similarly highlighted by Husby et al [33] in another randomized study. Even with good outcomes in the muscle strength force as measured by Kendall's criteria [22], this method may be imprecise when compared with a previously described method using a dynamometer, an instrument that is thought to have higher measurement accuracy [26,28,37]. Kendall's criteria [22] can be incorrect due to the negative influence of the patient's pain as well as due to measurements obtained by different researchers.…”

Resistance training induces qualitative changes in muscle morphology, muscle architecture, and muscle function in elderly postoperative patients

“…Muscle strength was measured as the maximal voluntary knee extension (peak moment, N ⅐ m) during concentric quadriceps contraction in an isokinetic dynamometer (KinCom) at 60°/s and 180°/s (46). Moment values were corrected for gravity of the lower limb and normalized to body weight.…”

“…Despite this, resistance training is still rarely used in the rehabilitation of elderly patients and especially in the elderly who have been hospitalized. Previously, we have studied the neuromuscular and functional changes, before and after unilateral resistance training, neuromuscular electrical stimulation, and a standard rehabilitation program in elderly patients recovering from hip replacement surgery (46,47). These results indicated that resistance training is more effective to restore muscle mass, contractile rate of force development, and functional performance than rehabilitation regimes based on functional exercises and electrical stimulation (46,47).…”

“…Previously, we have studied the neuromuscular and functional changes, before and after unilateral resistance training, neuromuscular electrical stimulation, and a standard rehabilitation program in elderly patients recovering from hip replacement surgery (46,47). These results indicated that resistance training is more effective to restore muscle mass, contractile rate of force development, and functional performance than rehabilitation regimes based on functional exercises and electrical stimulation (46,47). However, although muscle architecture has been shown to be an important factor for muscle function in young individuals (1), no studies have previously investigated the changes in muscle fiber morphology and muscle architecture with different types of intervention in the elderly.…”