Difference In Metabolic Stress During Resistance Exercise With Blood Flow Restriction Between Sprinters And Endurance Runners

Abstract

PURPOSE: We previously demonstrated that a low-intensity resistance exercise with blood flow restriction (BFR) significantly enhanced skeletal muscle metabolic stress (as indicated by phosphocreatine depletion, intramuscular pH decrease, and H2PO4- increase). However, we have observed a considerable individual difference in those responses (J Appl Physiol. 2009). It is possible that the differences might be due to muscle fiber specificities. Therefore, we investigated metabolic responses during low-intensity resistance exercise with BFR between the two different types of track athletes (sprinters and endurance runners). METHODS: Twelve age-matched track athletes (endurance/sprint group, 6/6, 20.7±1.4 yrs) were participated and performed unilateral planter-flexion (30 repetition/min) for 2 min. Exercise protocols were as follows: low-intensity exercise (L) using a load of 20% of one-repetition maximum (1 RM), L with BFR (LBFR), and high-intensity exercise using 65% 1 RM (H). Metabolic stress was evaluated at rest and during exercise by using 31P-magnetic resonance spectroscopy. BFR was carried out by pneumatic cuff around the thigh with 1.3 times of systolic blood pressure. The respiratory gas analysis was performed by breath-by-breath apparatus on treadmill with modified Bruce's protocol. RESULTS: Endurance group showed higher peak oxygen uptake than sprint group (74.3 ± 7.5 vs. 62.7 ± 4.7 ml/min/kg, p<0.01). Phosphocreatine levels at the end of exercise in LBFR were significantly smaller in endurance group compared with sprint group (13.7 ± 0.3 vs 18.4 ± 1.2 mM, p<0.05), although those in L were significantly greater in endurance group than in sprint group (31.5 ± 0.6 vs 27.7 ± 1.7 mM, p<0.05). Those were similar in H between endurance and sprint group. The changes in intramuscular pH and H2PO4- did not show a statistical difference between the two groups. The amount of phosphocreatine depletion was significantly correlated with peak oxygen uptake (r=0.783, p<0.01). CONCLUSIONS: It was suggested that the effects of low-intensity resistance exercise with blood flow restriction might become greater in endurance runner with higher aerobic capacity. Muscle fiber types, vascular function, specific tension, muscle volume, and training status could concern the present results.