Noninvasive Monitoring of Training Induced Muscle Adaptation with -MRS: Fibre Type Shifts Correlate with Metabolic Changes

Abstract

Purpose. To evaluate training induced metabolic changes noninvasively with 31P magnetic resonance spectroscopy (31P-MRS) for measuring muscle fibre type adaptation. Methods. Eleven volunteers underwent a 24-week training, consisting of speed-strength, endurance, and detraining (each 8 weeks). Prior to and following each training period, needle biopsies and 31P-MRS of the resting gastrocnemius muscle were performed. Fibre type distribution was analyzed histologically and tested for correlation with the ratios of high energy phosphates ([PCr]/[Pi], [PCr]/[βATP] and [PCr + Pi]/[βATP]). The correlation between the changes of the 31P-MRS parameters during training and the resulting changes in fibre composition were also analysed. Results. We observed an increased type-II-fibre proportion after speed-strength and detraining. After endurance training the percentage of fast-twitch fibres was reduced. The progression of the [PCr]/[Pi]-ratio was similar to that of the fast-twitch fibres during the training. We found a correlation between the type-II-fibre proportion and [PCr]/[Pi] (r = 0.70, P < 0.01) or [PCr]/[βATP] (r = 0.69, P < 0.01); the correlations between its changes (delta) and the fibre-shift were significant as well (delta[PCr]/[Pi] r = 0.66, delta[PCr]/[βATP] r = 0.55, P < 0.01). Conclusion. Shifts in fibre type composition and high energy phosphate metabolite content covary in human gastrocnemius muscle. Therefore 31P-MRS might be a feasible method for noninvasive monitoring of exercise-induced fibre type transformation.

Localized semi-LASER dynamic 31P magnetic resonance spectroscopy of the soleus during and following exercise at 7 T

“…Reproducing the same effect of exercise (i.e., equal activation of SOL and hence PCr depletion) by repeating the measurements after a longer period of several months was attempted in three subjects and found to be challenging. Possible reasons for larger variability (data not shown) are that the subjects may have distributed the exercise load to individual calf muscles differently, when asked to perform the same exercise after a long time, and that training state and living circumstances can change over longer periods [32], which could influence the measured parameters. Yet, all measurements performed to test reproducibility in SOL resulted in values that corresponded to low metabolic activation, which confirms that the striking differences observed in data from SOL and GM were not caused by repeating the exercise within 25 min, but represent intrinsic differences in the metabolic response of these muscles to the same exercise.…”

Molecular imaging in masseter muscle observed by muscle function magnetic resonance imaging and 31P‐magnetic resonance spectroscopy in patients with a jaw deformity

“…The prolonged T2 value in the patient group may have been due to the increased acidification tendency in the masseter muscle under the experimental clenching compared with the healthy control group (Chikui et al, 2010; Shiraishi et al, 2011). Several studies utilizing 31 P‐MRS confirmed the existence of a strong relationship between transverse relaxation properties and the metabolic state in large skeletal muscles, such as the gastrocnemius or the wrist flexor muscles, engaged in exercise (Hoff et al, 2013; Mizuno et al, 1994; Segal, 2007; Stutzig et al, 2016; Vandenborne et al, 2000). As shown in semi‐quantitative evaluation of the pH, that in the skeletal class III patients was significantly lower than that of the healthy control group at rest and recovery in the present study.…”

“…Molecular imaging by magnetic resonance imaging (MRI) enables the visualization of the intra‐individual molecular movements inside a live body without damaging the individual. Thus far, for skeletal muscles with large cross‐sectional areas, such as the quadriceps muscles, molecular imaging has been carried out using muscle functional MRI (mfMRI) (Akima et al, 2004; Cagnie et al, 2011; Kinugasa & Akima, 2005; Segal, 2007) and phosphorus‐31 nuclear magnetic resonance spectroscopy ( 31 P‐MRS) (Hoff et al, 2013; Stutzig et al, 2016; van Oorschot et al, 2013), which are both noninvasive examinations. These techniques allow physiological information and biochemical information of the muscles to be obtained simultaneously enabling a comparison of their findings.…”

β‐GPA treatment leads to elevated basal metabolic rate and enhanced hypoxic exercise tolerance in mice

“…During exercise, the creatine kinase (CK) reaction catalyzes the net transfer of a phosphoryl group from PCr to ADP, forming ATP and creatine, whereas the reaction operates in the net reverse direction during recovery from exercise when ATP demand returns to resting levels (Ellington 2001). Unlike the transient effects on energy state that occur during short-term exercise, chronic endurance exercise training can lead to a shift toward more aerobic, slow-twitch muscle fiber types, which have a persistently lower resting PCr/ATP ratio (Bernus et al 1993;Hoff et al 2013) and higher resting metabolic rate than fasttwitch fiber types (Blei et al 1997).…”