Takuma Morishima

Compression garment promotes muscular strength recovery after resistance exercise.

PURPOSE This study aimed to investigate the effects of wearing a compression garment (CG) for 24 h on changes in muscular strength and blood parameters over time after resistance exercise. METHODS Nine trained men conducted resistance exercises (10 repetitions of 3-5 sets at 70% of one-repetition maximum (1RM) for nine exercises) in two trials, wearing either a CG or a normal garment (CON) for 24 h after exercise. Recovery of muscular strength, blood parameters, muscle soreness, and upper arm and thigh circumference were compared between the trials. RESULTS Both trials showed decreases in maximal strength after the exercise (P < 0.05). However, the CG trial showed faster recovery of one-repetition maximum for the chest press from 3 to 8 h after exercise (P < 0.05). Recovery of maximal knee extension strength was also improved in the CG trial 24 h after exercise (P < 0.05). The CG trial was associated with lower muscle soreness and subjective fatigue scores the following morning (P < 0.05). The upper arm and thigh circumferences were significantly higher during the recovery period in the CON trial, whereas no change was observed in the CG trial. Blood lactate, insulin like growth factor-1, free testosterone, myoglobin, creatine kinase, interleukin 6, and interleukin 1 receptor antagonist concentrations for 24 h after exercise were similar in both trials. CONCLUSIONS Wearing a CG after resistance exercise facilitates the recovery of muscular strength. Recovery for upper body muscles significantly improved within 3-8 h after exercise. However, facilitation of recovery of lower limb muscles by wearing the CG took a longer time.

Whole body, regional fat accumulation, and appetite-related hormonal response after hypoxic training.

The present study was conducted to determine change in regional fat accumulation and appetite‐related hormonal response following hypoxic training. Twenty sedentary subjects underwent hypoxic (n = 9, HYPO, FiO2 = 15%) or normoxic training (n = 11, NOR, FiO2 = 20·9%) during a 4‐week period (3 days per week). They performed a 4‐week training at 55% of maximal oxygen uptake ( V· O2max) for each condition. Before and after the training period, V· O2max, whole body fat mass, abdominal fat area, intramyocellular lipid content (IMCL), fasting and postprandial appetite‐related hormonal responses were determined. Both groups showed a significant increase in V· O2max following training (P<0·05). Whole body and segmental fat mass, abdominal fat area, IMCL did not change in either group. Fasting glucose and insulin concentrations significantly reduced in both groups (P<0·05). Although area under the curve for the postprandial blood glucose concentrations significantly decreased in both groups (P<0·05), the change was significantly greater in the HYPO group than in the NOR group (P<0·05). Changes in postprandial plasma ghrelin were similar in both groups. A significant reduction of postprandial leptin response was observed in both groups (P<0·05), while postprandial glucagon‐like peptide‐1 (GLP‐1) concentrations increased significantly in the NOR group only (P<0·05). In conclusion, hypoxic training for 4 weeks resulted in greater improvement in glucose tolerance without loss of whole body fat mass, abdominal fat area or IMCL. However, hypoxic training did not have synergistic effect on the regulation of appetite‐related hormones.

Ghrelin, GLP-1, and leptin responses during exposure to moderate hypoxia.

Severe hypoxia has been indicated to cause acute changes in appetite-related hormones, which attenuate perceived appetite. However, the effects of moderate hypoxia on appetite-related hormonal regulation and perceived appetite have not been elucidated. Therefore, we examined the effects of moderate hypoxia on appetite-related hormonal regulation and perceived appetite. Eight healthy males (21.0 ± 0.6 years; 173 ± 2.3 cm; 70.6 ± 5.0 kg; 23.4 ± 1.1 kg/m(2)) completed two experimental trials on separate days: a rest trial in normoxia (FiO2 = 20.9%) and a rest trial in hypoxia (FiO2 = 15.0%). The experimental trials were performed over 7 h in an environmental chamber. Blood samples and scores of subjective appetite were collected over 7 h. Standard meals were provided 1 h (745 kcal) and 4 h (731 kcal) after initiating exposure to hypoxia or normoxia within the chamber. Although each meal significantly reduced plasma active ghrelin concentrations (P < 0.05), the response did not differ significantly between the trials over 7 h. No significant differences in the area under the curves for plasma active ghrelin concentrations over 7 h were observed between the two trials. No significant differences were observed in glucagon-like peptide 1 or leptin concentrations over 7 h between the trials. The subjective feeling of hunger and fullness acutely changed in response to meal ingestions. However, these responses were not affected by exposure to moderate hypoxia. In conclusion, 7 h of exposure to moderate hypoxia did not change appetite-related hormonal responses or perceived appetite in healthy males.

Impact of exercise and moderate hypoxia on glycemic regulation and substrate oxidation pattern.

Objective We examined metabolic and endocrine responses during rest and exercise in moderate hypoxia over a 7.5 h time courses during daytime. Methods Eight sedentary, overweight men (28.6±0.8 kg/m2) completed four experimental trials: a rest trial in normoxia (FiO2 = 20.9%, NOR-Rest), an exercise trial in normoxia (NOR-Ex), a rest trial in hypoxia (FiO2 = 15.0%, HYP-Rest), and an exercise trial in hypoxia (HYP-Ex). Experimental trials were performed from 8:00 to 15:30 in an environmental chamber. Blood and respiratory gas samples were collected over 7.5 h. In the exercise trials, subjects performed 30 min of pedaling exercise at 60% of VO2max at 8:00, 10:30, and 13:00, and rested during the remaining period in each environment. Standard meals were provided at 8:30, 11:00, and 13:30. Results The areas under the curves for blood glucose and serum insulin concentrations over 7.5 h did not differ among the four trials. At baseline, %carbohydrate contribution was significantly higher in the hypoxic trials than in the normoxic trials (P<0.05). Although exercise promoted carbohydrate oxidation in the NOR-Ex and HYP-Ex trials, %carbohydrate contribution during each exercise and post-exercise period were significantly higher in the HYP-Ex trial than in the NOR-Ex trial (P<0.05). Conclusion Three sessions of 30 min exercise (60% of VO2max) in moderate hypoxia over 7.5 h did not attenuate postprandial glucose and insulin responses in young, overweight men. However, carbohydrate oxidation was significantly enhanced when the exercise was conducted in moderate hypoxia.

Effect of sprint training: Training once daily versus twice every second day

Abstract This study compared training adaptations between once daily (SINGLE) and twice every second day (REPEATED) sprint training, with same number of training sessions. Twenty physically active males (20.9 ± 1.3 yr) were assigned randomly to the SINGLE (n = 10) or REPEATED (n = 10) group. The SINGLE group trained once per day (5 days per week) for 4 weeks (20 sessions in total). The REPEATED group conducted two consecutive training sessions on the same day, separated by a rest period of 1 h (2–3 days per week) for 4 weeks (20 sessions in total). Each training session consisted of three consecutive 30-s maximal pedalling sets with a 10-min rest between sets. Before and after the training period, the power output during two bouts of 30-s maximal pedalling, exercise duration during submaximal pedalling and resting muscle phosphocreatine (PCr) levels were evaluated. Both groups showed significant increases in peak and mean power output during the two 30-s bouts of maximal pedalling after the training period (P < 0.05). The groups showed similar increases in after the training period (P < 0.05). The REPEATED group showed a significant increase in the onset of blood lactate accumulation (OBLA) after the training period (P < 0.05), whereas no change was observed in the SINGLE group. The time to exhaustion at 90% of and muscle PCr concentration at baseline did not change significantly in either group. Sprint training twice every second day improved OBLA during endurance exercise more than the same training once daily.

Effects of different periods of hypoxic training on glucose metabolism and insulin sensitivity

This study examined the effects of different periods of hypoxic training on glucose metabolism. Sedentary subjects underwent hypoxic training (FiO2 = 15·0%) for either 2 weeks (2‐week group; n = 11) or 4 weeks (4‐week group; n = 10). The 2‐week group conducted training sessions on 6 days week−1 for 2 weeks, whereas the 4‐week group conducted training sessions on 3 days week−1 for 4 weeks. Body fat mass or abdominal fat area did not change after training period in either group. VO2max increased in both groups after training period (42 ± 2 versus 43 ± 2 ml min−1 kg−1 in 2‐week group, 41 ± 1 versus 42 ± 2 ml min−1 kg−1 in 4‐week group). Both groups showed a reduction in mean blood pressure after training period (92 ± 3 versus 90 ± 3 mmHg in 2‐week group, 91 ± 2 versus 87 ± 2 mmHg in 4‐week group, P≤0·05). No change was observed in blood glucose response after glucose ingestion after training period. However, area under the curve for serum insulin concentrations after glucose ingestion significantly decreased in only 4‐week group (6910 ± 763 versus 5812 ± 872 μIU ml−1 120 min, P≤0·05). In conclusion, hypoxic training reduced blood pressure with independent on training duration. However, a longer period of hypoxic training led to greater improvements in insulin sensitivity compared with equivalent training over a shorter period, suggesting that hypoxic training programmes for more than 4 weeks might be more beneficial for improving insulin sensitivity.

Augmented Carbohydrate Oxidation under Moderate Hypobaric Hypoxia Equivalent to Simulated Altitude of 2500 m

Hypoxia itself stimulates glucose uptake mediated by a mechanism independent of insulin. However, whether moderate hypoxia causes similar metabolic effect in humans remains unclear. The present study aimed to determine glycemic regulation following glucose load at a simulated moderate altitude of 2,500 m. Eight healthy young males (mean ± standard error: 24 ± 1 years; 171.3 ± 1.6 cm; 66.9 ± 3.7 kg; 22.8 ± 1.0 kg/m(2)) consumed 75 g of glucose solution under either hypobaric condition (560 mmHg) or normobaric condition (745 mmHg). In the hypobaric chamber, the oxygen partial pressure is proportionally reduced with a reduction of atmospheric pressure, consequently leading to the hypoxic condition. Plasma glucose and serum insulin concentrations increased significantly following glucose load in both conditions (P < 0.05). However, no significant interaction (condition × time) or main effect for condition was observed. There were no significant differences in serum glycerol, plasma epinephrine, or plasma norepinephrine concentrations between the two conditions. No significant differences between the conditions were observed in changes in VO2 or VCO2. However, the hypobaric condition showed significantly higher respiratory exchange ratio (VCO2/VO2) at 90 and 120 min following glucose load (P < 0.05 vs. normobaric condition), suggesting that carbohydrate oxidation following glucose load was enhanced in moderate hypobaric hypoxia. In conclusion, acute exposure to moderate hypobaric hypoxia significantly augmented carbohydrate oxidation following the glucose load, without affecting glucose or insulin responses. Thus, a short-time exposure to moderate hypobaric hypoxia may be beneficial for people with impaired glucose tolerance.