Effect of training on the activity of five muscle enzymes studied on elite cross‐country skiers

Abstract

This study examines the effect of training intensity on the activity of enzymes in m. vastus lateralis. Elite junior cross-country skiers of both sexes trained 12-15 h weeks-1 for 5 months at either moderate (60-70% of VO2max, MIG) or high training intensity (80-90% of the VO2max, close to the lactate threshold; HIG). Muscle biopsies for enzyme analyses and fibre typing were taken before and after the training period. Histochemical analyses on single fibres were done for three enzymes (succinate dehydrogenase [SDH], hydroxybutyrate dehydrogenase [HBDH], glycerol-3-phosphate dehydrogenase [GPDH]), while the activity of citrate synthase [CS] and phosphofructokinase [PFK] was measured on whole biopsies. The activity of GPDH was low in ST fibres and high in FT fibres. The activity of SDH and HBDH was high in both ST and FTa fibres but low in the FTb fibres. The HIG increased their performance more than the MIG did during the training period as judged from scores on a 20-min run test. The SDH activity rose by 6% for the HIG (P < 0.02). No effects of training were found in the activities of CS, HBDH or GPDH, neither in the two training groups nor for the two genders (P > or = 0.16). The PFK activity fell by 10% for the HIG (P=0.02), while no change was found for the MIG. For GPDH, CS and SDH the women's activity was approximately 20% less than the value for the men (P < 0.03). For PFK and HBDH there was no sex difference (P > or = 0.27). There were positive correlations between the activity of three of the enzymes (CS, SDH and GPDH) and the performance parameters (VO2max, cross-country skiing and running performance; r > or = 0.6, P < 0.01). No correlations were found between the PFK or HBDH activities and the performance parameters (r < or = 0.16, P > 0.05). This study suggests that intensities near the lactate threshold affect biochemical and physiological parameters examined in this study as well as the performance of elite skiers, and that the rate-limiting enzymes may be more sensitive to training than non-rate-limiting enzymes.

Effect of training with different intensities and volumes on muscle fibre enzyme activity and cross sectional area in the m. triceps brachii

“…Digital image analysis was performed according to Evertsen et al (1999). In brief: Digital images of cryostat sections were captured with a CCD camera (Kappa, Germany) mounted on top of a microscope (Leitz, Germany).…”

“…Endurance athletes often perform high volumes of continuous low and moderate intensity training (e.g., Evertsen et al 1999), thus investing large amounts of time in this type of training. Consequently, there is considerable interest in the eYcacy of less time consuming types of training like low volume, intensive intermittent training (Coyle 2005).…”

Distribution of Training Volume and Intensity of Elite Male and Female Track and Marathon Runners

“…Other studies have shown significant improvements in V · O 2 max and running speed at anaerobic threshold (vAT) in elite endurance athletes using the anaerobic threshold training model (80-87% of V · O 2 max/ 82-92% of HR max ) [21][22][23] . Indeed, the runners with greatest success, the Kenyan runners, do a lot of training at this intensity 24,25 .…”

Inhibition of calcineurin increases monocarboxylate transporters 1 and 4 protein and glycolytic enzyme activities in rat soleus muscle

“…It is therefore plausible that a fibre typespecific difference in glycolytic enzyme activity may result from a difference in calcineurin activity. Furthermore, it is likely that the decreased activities of glycolytic enzyme, as well as a fibre type changes due to endurance exercise training 34,35 or chronic electrical stimulation, 1,14,16 are caused, at least in part, by the activation of calcineurin.…”