ABSTRACT
In this study, we hypothesized that athletes involved in 5-6 months of sprint-type training would display higher levels of proteins and processes involved in muscle energy supply and utilization. Tissue was sampled from the vastus lateralis of 13 elite ice hockey players (peak oxygen consumption = 51.8 ± 1.3 mL·kg(-1)·min(-1); mean ± standard error) at the end of a season (POST) and compared with samples from 8 controls (peak oxygen consumption = 45.5 ± 1.4 mL·kg(-1)·min(-1)) (CON). Compared with CON, higher activities were observed in POST (p < 0.05) only for succinic dehydrogenase (3.32 ± 0.16 mol·(mg protein)(-1)·min(-1) vs. 4.10 ± 0.11 mol·(mg protein)(-1)·min(-1)) and hexokinase (0.73 ± 0.05 mol·(mg protein)(-1)·min(-1) vs. 0.90 ± 0.05mol·(mg protein)(-1)·min(-1)) but not for phosphorylase, phosphofructokinase, and creatine phosphokinase. No differences were found in Na(+),K(+)-ATPase concentration (ß(max): 262 ± 36 pmol·(g wet weight)(-1) vs. 275 ± 27 pmol·(g wet weight)(-1)) and the maximal activity of the sarcoplasmic reticulum Ca(2+)-ATPase (98.1 ± 6.1 µmol·(g protein)(-1)·min(-1) vs. 102 ± 3.3 µmol·(g protein)(-1)·min(-1)). Cross-sectional area was lower (p < 0.05) in POST but only for the type IIA fibres (6312 ± 684 µm(2) vs. 5512 ± 335 µm(2)), while the number of capillary counts per fibre and the capillary to fibre area ratio were generally higher (p < 0.05). These findings suggest that elite trained ice hockey players display elevations only in support of glucose-based aerobic metabolism that occur in the absence of alterations in excitation-contraction processes.
Subject(s)
Athletic Injuries/metabolism , Athletic Injuries/pathology , Cumulative Trauma Disorders/metabolism , Cumulative Trauma Disorders/pathology , Hockey , Sarcoplasmic Reticulum/metabolism , Sarcoplasmic Reticulum/pathology , Adult , Creatine Kinase/metabolism , Energy Metabolism , Glucose/metabolism , Hexokinase/metabolism , Humans , Musculoskeletal Physiological Phenomena , Oxygen Consumption/physiology , Phosphofructokinases/metabolism , Phosphorylases/metabolism , Quadriceps Muscle/metabolism , Quadriceps Muscle/physiology , Sarcoplasmic Reticulum Calcium-Transporting ATPases/metabolism , Sodium-Potassium-Exchanging ATPase/metabolism , Succinate Dehydrogenase/metabolism , Teaching/methods , Young AdultABSTRACT
PURPOSE: This study aimed to evaluate the effect of an exercise program of two different intensities, with nutritional control, on gestational weight gain (GWG), infant birth weight, and maternal weight retention at 2 months postpartum (2 mopp). METHODS: Pregnant women (prepregnancy body mass index = 18.5-24.9 kg·m) were randomized at study entry (16-20 wk of gestation) to a low-intensity (LI, 30% HR reserve (HRR), n = 23) or moderate-intensity (MI, 70% HRR, n = 26) exercise program, with nutritional control. The exercise program consisted of walking sessions three to four times per week, gradually increasing exercise time from 25 to 40 min per session. Forty-five normal-weight women who did not participate in any structured exercise program during pregnancy and had singleton births were used as a historical control group. RESULTS: Total GWG was higher in the control group (18.3 ± 5.3 kg) compared with the LI (15.3 ± 2.9 kg, P = 0.01) and MI (14.9 ± 3.8 kg, P = 0.003) groups. During the intervention, GWG was similar in both intervention groups, with weekly rates of weight gain of 0.49 ± 0.1 and 0.47 ± 0.1 kg·wk in the LI and MI groups, respectively. Excessive GWG during the intervention was prevented in 70% of the women in the LI group and 77% of those in the MI group. Excessive GWG occurred before the intervention began. At 2 mopp, 18% and 28% of the women in the LI and MI groups, respectively, retained ≤2.0 kg compared with only 7% of those in the control group. Infant birth weight was not different between the groups. CONCLUSIONS: Results suggest that a prenatal nutrition and exercise program regardless of exercise intensity, reduced excessive GWG and decreased weight retention at 2 mopp in women of normal weight before pregnancy.
Subject(s)
Exercise/physiology , Nutritional Status/physiology , Pregnancy/physiology , Weight Gain/physiology , Adult , Body Mass Index , Female , Humans , Postpartum Period , Walking/physiologyABSTRACT
We hypothesized that a season of ice hockey would result in extensive remodeling of muscle. Tissue sampled from the vastus lateralis of 15 players (age = 20.6 ± 0.4 years; mean ± SE) prior to (PRE) and following (POST) a season was used to characterize specific adaptations. Measurement of representative metabolic pathway enzymes indicated higher maximal activities in POST than in PRE (p < 0.05) for succinic dehydrogenase (3.26 ± 0.31 vs. 3.91 ± 0.11 mol mg protein(-1) min(-1)), citrate synthase (7.26 ± 0.70 vs. 8.70 ± 0.55 mol mg protein(-1) min(-1)), and phosphofructokinase (12.8 ± 1.3 vs. 14.4 ± 0.96 mol mg protein(-1) min(-1)) only. The season resulted in an increase in Na+-K+-ATPase concentration (253 ± 6.3 vs. 265 ± 6.0 pmol g(-1) wet weight), a decrease (p < 0.05) in maximal activity of the sarcoplasmic reticulum Ca2+-ATPase (107 ± 4.2 micromol g protein(-1) min(-1) vs. 92.0 ± 4.6 micromol g protein(-1) min(-1)), and no change in the distribution (%) of fibre types. A smaller (p < 0.05) cross-sectional area (CSA) for both type I (-11.7%) and type IIA (-18.2%) fibres and a higher (p < 0.05) capillary count/CSA for type I (+17.9%) and type IIA (+17.2%) were also found over the season. No changes were found in peak oxygen consumption (51.4 ± 1.2 mL kg(-1) min(-1) vs. 52.3 ± 1.3 mL kg(-1) min(-1)). The results suggest, based on the alterations in oxidative and perfusion potentials and muscle mass, that the dominant adaptations are in support of oxidative metabolism, which occurs at the expense of fibre CSA and possibly force-generating potential.
