Resistance training with vascular occlusion: metabolic adaptations in human muscle.

UNLABELLED: Two recent studies have reported increases in strength and whole muscle cross-sectional area after low-intensity resistance training (LIT) with vascular occlusion (OCC) that are greater than LIT alone (e.g., 22, 25). The OCC stress might be expected to induce metabolic alterations that are consistent with compromised oxygen delivery rather than an increase in strength per se, but this has not been studied.
PURPOSE: We examined the effect of LIT and LIT+OCC on resting metabolites in m. biceps brachii and elbow flexor strength.
METHODS: Eight men (19.5 +/- 0.4 yr) performed 8 wk of LIT at approximately 50% of one-repetition maximum (2 sessions per week; 3-6 sets, 8-10 repetitions, final set to failure); one arm trained with OCC and the other without (CON). :Biopsies obtained before and 72 h after the final training bout revealed that resting [glycogen] was higher (P <or= 0.05) in both arms after LIT (CON: 452 +/- 20 vs 325 +/- 28, OCC: 501 +/- 12 vs 332 +/- 28 mmol.kg-1 dry weight) and the increase was larger in the OCC arm (P <or= 0.05). Resting [ATP] was lower (P <or= 0.05) after LIT in both arms (CON: 20.5 +/- 0.5 vs 22.8 +/- 0.7, OCC: 18.2 +/- 0.6 vs 23.1 +/- 0.5 mmol.kg-1 dry weight), and the decrease was larger in the OCC arm (P <or= 0.05). Maximal isotonic and isokinetic elbow flexor strength increased (P <or= 0.05) after training to a similar extent in both arms.
CONCLUSION: We conclude that [glycogen] was increased and [ATP] was decreased in resting human muscle, 72 h after an 8-wk LIT protocol. OCC potentiated the metabolic changes, perhaps by inducing an ischemic stimulus that enhanced muscle glucose transport and adenine nucleotide catabolism after LIT, but did not augment the increases in strength.