Noninvasive monitoring of deterioration in skeletal muscle function with forearm cast immobilization and the prevention of deterioration

BACKGROUND: In this research inactivity was simulated by immobilizing the forearm region in a plaster cast. Changes in skeletal muscle oxidative function were measured using near-infrared spectroscopy (NIRS), and the preventative effect of the training protocol on deterioration of skeletal muscle and the clinical utility of NIRS were examined. METHODS: Fourteen healthy adult men underwent immobilization of the forearm of the non-dominant arm by plaster cast for 21 days. Eight healthy adult subjects were designated as the immobilization group (IMM) and six were designated as the immobilization + training group (IMM+TRN). Grip strength, forearm circumference and dynamic handgrip exercise endurance were measured before and after the 21-day immobilization period. Using NIRS, changes in oxidative function of skeletal muscles were also evaluated. Muscle oxygen consumption recovery was recorded after the completion of 60 seconds of 40% maximum voluntary contraction (MVC) dynamic handgrip exercise 1 repetition per 4 seconds and the recovery time constant (TcVO(2)mus) was calculated. RESULTS: TcVO(2)mus for the IMM was 59.7 ± 5.5 seconds (average ± standard error) before immobilization and lengthened significantly to 70.4 ± 5.4 seconds after immobilization (p < 0.05). For the IMM+TRN, TcVO(2)mus was 78.3 ± 6.2 seconds before immobilization and training and shortened significantly to 63.1 ± 5.6 seconds after immobilization and training (p < 0.05). CONCLUSIONS: The training program used in this experiment was effective in preventing declines in muscle oxidative function and endurance due to immobilization. The experimental results suggest that non-invasive monitoring of skeletal muscle function by NIRS would be possible in a clinical setting

Temporal increase in muscle cross-sectional area as an acute effect of resistance exercise in resistance-trained and untrained individuals

The purpose of this study was to compare the temporal increase in muscle cross-sectional area (CSA) as the acute response of resistance exercise (RE) between resistance-trained and untrained groups, and investigate the factors that affect the muscle CSA. Resistance-trained (n = 14) and untrained (n = 14) subjects performed four kinds of triceps brachii RE. Muscle CSA and intracellular hydration (IH), were measured prior to and 5-, 30-, and 60-minute after RE. Pearson's correlation coefficient was calculated to clarify the relationships among percent increases in muscle CSA and IH, area under the Oyx-Hb curve, blood lactate concentration, and % maximum voluntary contraction (MVC)-root-mean-square (RMS) of electromyogram (EMG). At 5-minute after RE, muscle CSA increased significantly to 120.2 ± 6.3% in the resistance-trained group and 105.5 ± 2.3% in the untrained group (p < 0.01). However, neither group showed a significant difference between the values before and 30-minute after RE. In the resistance-trained group, there was a significant increase in IH at 5-minute post-RH (p < 0.01), and correlations were found between percent increases in muscle CSA and IH (r = 0.70, p < 0.01), area under the Oxy-Hb curve (r = 0.77, p < 0.01), and % MVC-RMS of EMG (r = 0.72, p < 0.01). The findings of this study suggest that measurements of muscle CSA in studies of muscle hypertrophy should be performed 30-minute or more after the last resistance exercise session, and muscle pump exercises should be conducted just before participation in bodybuilding, and physique contests

Near infrared spectroscopy : what can it tell us about oxygen saturation in skeletal muscle?

Contains fulltext : mmubn000001_115818545.pdf (publisher's version ) (Open Access)Promotor : J. van Rossum111 p