Effects of Active and Passive Recoveries on Splitting of the Inorganic Phosphate Peak Determined by 31P-Nuclear Magnetic Resonance Spectroscopy

Abstract

Six male long-distance runners performed knee flexion exercises in a 2.1 T superconducting magnet. 31P MRS was used to investigate the splitting pattern of the inorganic phosphate (PI) peak during active and passive recovery. During exercise splitting of the Pi peak into two was observed (high and low pH) and after exercise the manner in which the Pi peak disappeared was different in passive and active recoveries. During passive recovery, in which exercise was not performed at all, the high-pH Pi peak disappeared more rapidly than the low-pH Pi peak. The low-pH Pi peak remained at a similar acidified chemical shift as during exercise, and then gradually disappeared during passive recovery. Conversely, during active recovery in which unloaded exercise was followed, the high-pH P, peak was reduced, but remained, whereas the low-pH Pi peak returned very quickly to the pre-exercise level and then disappeared. The recovery rate of the low pH during active recovery (0.095i0.019 pH unitdmin) was significantly faster than that during passive recovery (0.014i0.019 pH unitdmin) (p <O.Ol). The slow disappearance of the low pH Pi peak during passive recovery can be explained by the halting of glycogenolysis and an insufficient oxygen supply to resting glycolytic fibers, whereas the quick disappearance observed with active recovery would have been due to elevated sufficient oxygen supply and efficient removal of lactate as a result of the maintained blood flow. Oxy-myoglobin and hemoglobin was also measured with near infrared spectroscopy.~~

pH heterogeneity in tibial anterior muscle during isometric activity studied by31P-NMR spectroscopy

“…In these two cases (both after 60% MVC), the P i peak ascribed to the type I fibers disappears much faster than the one ascribed to the type II fibers. This can be explained by the pH dependency of the recovery of P i (10) and the higher oxidative capacity of the type I fibers (21) and is in agreement with the observations of others (1,18,19,24,29,30).…”

31P MRS evaluation of fatigue in anterior tibial muscle in postpoliomyelitis patients and healthy volunteers

“…Increase in P i and reduction in pH have been demonstrated to impair the contractile process by a reduced calcium sensitivity (Westerblad et al, 1991), a mechanism which might explain some of the differences in MVC after exercise. This pattern has also been seen by others, and may indicate a more equivalent proportion of type I and II fibres within the muscle (Yoshida et al, 1996). The cross-sectional area of the fibres was higher in the patients and the number of capillaries in contact with type I fibres in relation to the fibre area was significantly lower for the patients than for the controls (0AE6 and 1AE0 capillaries per lm 2 , respectively).…”

“…However, the pH of the high-pH peak was decreasing slowly during exercise and also had a very slow recovery. This pattern has also been seen by others, and may indicate a more equivalent proportion of type I and II fibres within the muscle (Yoshida et al, 1996). Patient P2 had earlier been thoroughly examined, showing normal muscle strength, large motor unit potentials (Table 1), large muscle fibre areas (mean 13AE2 · 10 3 lm 2 , about the same size of the type I and II fibres) and 35% type II fibres, which is remarkably high.…”

Effects of Active vs. Passive Recovery on Work Performed During Serial Supramaximal Exercise Tests

“…An effect of recovery mode on muscle glycogen is unlikely due to the short time course of recovery and previous investigations which demonstrated that active recovery does not increase muscle glycogen stores when compared with passive recovery [6,7,21]. Rapid correction of intracellular acidosis and replenishment of phosphocreatine by mechanisms independent of lactate transport during active recovery is another potential explanation of our findings [16,30].…”