High-intensity Training Group Research Articles

Effects of Exercise Training on Fat Loss and Lean Mass Gain in Mexican-American and Korean Premenopausal Women.

We investigated the effect of exercise training on body composition change in women. Nineteen Mexican-American and 18 Korean premenopausal overweight/obese women were randomized into one of the following groups: control, low-intensity training group (LI), and high-intensity training group (HI). Subjects completed 12 weeks of training at 50–56% maximal oxygen consumption (LI) or 65–70% maximal oxygen consumption (HI). Body composition components were measured at baseline and after training using dual-energy X-ray absorptiometry for Mexican-Americans, while whole-body composition was measured by the direct segmental multifrequency bioelectrical impedance analysis and abdominal fat was measured by single-slice computed tomography for Koreans. Data were analyzed using mixed-model repeated measures independent of age, ethnicity, and body mass index (BMI). Exercise training showed a significant effect on BMI, fat percentage, fat mass, lean mass, and visceral adipose tissue area. HI significantly decreased fat mass and fat percentage but increased lean mass (all P < 0.05). LI significantly reduced BMI, fat mass, fat percentage, and visceral adipose tissue area but increased lean mass (all P < 0.05). Exercise training had a beneficial effect on reducing BMI, fat percentage, fat mass, and visceral adipose tissue area but had no effect on increasing lean mass for Mexican-American and Korean premenopausal overweight/obese women.

The Effect of Different High-Intensity Periodization Models on Endurance Adaptations.

This study aimed to compare the effects of three different high-intensity training (HIT) models, balanced for total load but differing in training plan progression, on endurance adaptations. Sixty-three cyclists (peak oxygen uptake (V˙O2peak) 61.3 ± 5.8 mL·kg·min) were randomized to three training groups and instructed to follow a 12-wk training program consisting of 24 interval sessions, a high volume of low-intensity training, and laboratory testing. The increasing HIT group (n = 23) performed interval training as 4 × 16 min in weeks 1-4, 4 × 8 min in weeks 5-8, and 4 × 4 min in weeks 9-12. The decreasing HIT group (n = 20) performed interval sessions in the opposite mesocycle order as the increasing HIT group, and the mixed HIT group (n = 20) performed the interval prescriptions in a mixed distribution in all mesocycles. Interval sessions were prescribed as maximal session efforts and executed at mean values 4.7, 9.2, and 12.7 mmol·L blood lactate in 4 × 16-, 4 × 8-, and 4 × 4-min sessions, respectively (P < 0.001). Pre- and postintervention, cyclists were tested for mean power during a 40-min all-out trial, peak power output during incremental testing to exhaustion, V˙O2peak, and power at 4 mmol·L lactate. All groups improved 5%-10% in mean power during a 40-min all-out trial, peak power output, and V˙O2peak postintervention (P < 0.05), but no adaptation differences emerged among the three training groups (P > 0.05). Further, an individual response analysis indicated similar likelihood of large, moderate, or nonresponses, respectively, in response to each training group (P > 0.05). This study suggests that organizing different interval sessions in a specific periodized mesocycle order or in a mixed distribution during a 12-wk training period has little or no effect on training adaptation when the overall training load is the same.

High-Intensity Training Improves Exercise Performance in Elite Women Volleyball Players During a Competitive Season.

Purkhús, E, Krustrup, P, and Mohr, M. High-intensity training improves exercise performance in elite women volleyball players during a competitive season. J Strength Cond Res 30(11): 3066-3072, 2016-Elite women volleyball players (n = 25; mean ± SD: age, 19 ± 5 years; height, 171 ± 7 cm; weight, 63 ± 10 kg) volunteered to participate in the study. They were randomized into a high-intensity training (HIT; n = 13) group and a control (CON; n = 12) group. In addition to the normal team training and games, HIT performed 6-10 × 30-seconds all-out running intervals separated by 3-minute recovery periods 3 times per week during a 4-week in-season period whereas CON only completed the team training sessions and games. Preintervention and postintervention, all players completed the arrowhead agility test (AAT), a repeated sprint test (RST; 5 × 30 meters separated by 25 seconds of recovery), and the Yo-Yo Intermittent Recovery level 2 test (Yo-Yo IR2) followed by a-10 minute rest period and the Yo-Yo IR1 test. Mean running distance during HIT in week 1 was 152 ± 4 m and increased (p ≤ 0.05) by 4.6% (159 ± 3 m) in week 4. The AAT performance improved (p ≤ 0.05) by 2.3% (18.87 ± 0.97-18.44 ± 1.06 seconds) and RST by 4.3% postintervention in the HIT group only. Baseline RST fatigue index was 7.0 ± 2.9 and 6.2 ± 5.0% in HIT and CON, respectively, but was lowered (p ≤ 0.05) to 2.7 ± 3.0% posttraining in HIT and remained unaltered in CON (5.5 ± 5.0%). In HIT, Yo-Yo IR2 and Yo-Yo IR1 performance improved by 12.6 and 18.3% postintervention, respectively, with greater (p ≤ 0.05) Yo-yo IR1 change scores than in CON. In conclusion, additional high-intensity in-season training performed as interval running improved agility, repeated sprint ability, and high-intensity intermittent exercise performance in elite women volleyball players.

Efficacy of a Four-Week Uphill Sprint Training Intervention in Field Hockey Players.

Jakeman, JR, McMullan, J, and Babraj, JA. Efficacy of a four-week uphill sprint training intervention in field hockey players. J Strength Cond Res 30(10): 2761-2766, 2016-Current evidence increasingly suggests that very short, supramaximal bouts of exercise can have significant health and performance benefits. Most research conducted in the area, however, uses laboratory-based protocols, which can lack ecological validity. The purpose of this study was to examine the effects of a high-intensity sprint training program on hockey-related performance measures. Fourteen semiprofessional hockey players either completed a 4-week high-intensity training (HIT) intervention, consisting of a total of 6 sessions of HIT, which progressively increased in volume (n = 7), or followed their normal training program (Con; n = 7). Straight-line sprint speed, with and without a hockey stick and ball, and slalom sprint speed, with and without a hockey stick and ball, were used as performance indicators. Maximal sprint speed over 22.9 m was also assessed. On completion of the 4-week intervention, straight-line sprint speed improved significantly in the HIT group (∼3%), with no changes in performance for the Con group. Slalom sprint speed, both with and without a hockey ball, was not significantly different after the training program in either group. Maximal sprint speed improved significantly (12.1%) in the HIT group, but there was no significant performance change in the Con group. The findings of this study indicate that a short period of HIT can significantly improve hockey-related performance measures and could be beneficial to athletes and coaches in field settings.

Time Course of Exercise Training–Induced Muscle Strength Changes in Type 2 Diabetes

Purpose: To investigate longitudinal muscle strength changes in response to exercise training in people with type 2 diabetes. Methods: Twenty-one people with type 2 diabetes were randomly allocated to either a moderate or high-intensity exercise training group with the only difference between the groups being the prescribed exercise training intensity. Muscle strength (8 repetition maximum in kilograms) was measured weekly for 12 weeks using the chest press, leg press, row, and knee extension exercises. Muscle strength was expressed as the sum of 8 repetition maximum scores for each exercise. Results: Linear mixed models indicated significant gains in muscle strength (P &lt; .001) in both groups and no significant difference in gains in muscle strength (P = .47) between the groups. Pooled data from both groups indicated significant improvement in muscle strength (P &lt; .05) week-to-week beginning after week 1 and continued until week 9. Conclusion: Participation in either a moderate or high-intensity exercise training program can result in similar gains in muscle strength for people with type 2 diabetes. Muscle strength improvements can occur on a weekly basis for the first 8 weeks of exercise training, with a plateau in gains occurring at week 9 through week 12.

Combination of body mass-based resistance training and high-intensity walking can improve both muscle size and V˙O2 peak in untrained older women.

Here, we aimed to compare the effect of a combination of body mass-based resistance exercise and moderate-intensity (55% peak oxygen uptake [ V˙O2 peak]) walking or high-intensity (75% V˙O2 peak) walking on muscle size and V˙O2 peak in untrained older women. A total of 12 untrained older women (mean age 60 ± 2 years) were randomly assigned to either a moderate-intensity aerobic training group (n = 6) or high-intensity aerobic training group (n = 6). Both groups carried out body-mass based (lower body) resistance exercises (2 sets of 10 repetitions) on 3 days/week for 8 weeks. Between these exercises, the participants in the moderate-intensity aerobic training group walked at a previously determined speed equivalent to 55% V˙O2 peak, whereas those in the high-intensity aerobic training group walked at a speed equivalent to 75% V˙O2 peak. Muscle thickness of the anterior aspect of the thigh and maximal isokinetic knee extension strength significantly increased in both groups (P < 0.01); these relative changes were negatively correlated with the absolute muscle thickness of the anterior aspect of the thigh value and the relative value of maximal knee strength to body mass at pre-intervention, respectively. A significant group × time interaction was noted for V˙O2 peak (P < 0.05), which increased only in the high-intensity aerobic training group. Body mass-based resistance training significantly induced muscle hypertrophy in untrained older women. In particular, lower muscle thickness before intervention was associated with greater training-induced growth. Furthermore, V˙O2 peak can be increased by combined circuit training involving low-load resistance exercise and walking, particularly when a relatively high intensity of walking is maintained. Geriatr Gerontol Int 2017; 17: 779-784.

Effects of moderate- and high-intensity chronic exercise on brain-derived neurotrophic factor expression in fast and slow muscles.

Brain-derived neurotrophic factor (BDNF) protein expression is sensitive to cellular activity. In the sedentary state, BDNF expression is affected by the muscle phenotype. Eighteen Wistar rats were divided into the following 3 groups: sedentary (S); moderate-intensity training (MIT); and high-intensity training (HIT). The training protocol lasted 8 weeks. Forty-eight hours after training, total RNA and protein levels in the soleus and plantaris muscles were obtained. In the plantaris, the BDNF protein level was lower in the HIT than in the S group (P < 0.05). A similar effect was found in the soleus (without significant difference). In the soleus, higher Bdnf mRNA levels were found in the HIT group (P < 0.001 vs. S and MIT groups). In the plantaris muscle, similar Bdnf mRNA levels were found in all groups. These results indicate that high-intensity chronic exercise reduces BDNF protein level in fast muscles and increases Bdnf mRNA levels in slow muscles.

High-intensity training reduces intermittent hypoxia-induced ER stress and myocardial infarct size.

Chronic intermittent hypoxia (IH) is described as the major detrimental factor leading to cardiovascular morbimortality in obstructive sleep apnea (OSA) patients. OSA patients exhibit increased infarct size after a myocardial event, and previous animal studies have shown that chronic IH could be the main mechanism. Endoplasmic reticulum (ER) stress plays a major role in the pathophysiology of cardiovascular disease. High-intensity training (HIT) exerts beneficial effects on the cardiovascular system. Thus, we hypothesized that HIT could prevent IH-induced ER stress and the increase in infarct size. Male Wistar rats were exposed to 21 days of IH (21-5% fraction of inspired O2, 60-s cycle, 8 h/day) or normoxia. After 1 wk of IH alone, rats were submitted daily to both IH and HIT (2 × 24 min, 15-30m/min). Rat hearts were either rapidly frozen to evaluate ER stress by Western blot analysis or submitted to an ischemia-reperfusion protocol ex vivo (30 min of global ischemia/120 min of reperfusion). IH induced cardiac proapoptotic ER stress, characterized by increased expression of glucose-regulated protein kinase 78, phosphorylated protein kinase-like ER kinase, activating transcription factor 4, and C/EBP homologous protein. IH-induced myocardial apoptosis was confirmed by increased expression of cleaved caspase-3. These IH-associated proapoptotic alterations were associated with a significant increase in infarct size (35.4 ± 3.2% vs. 22.7 ± 1.7% of ventricles in IH + sedenary and normoxia + sedentary groups, respectively, P < 0.05). HIT prevented both the IH-induced proapoptotic ER stress and increased myocardial infarct size (28.8 ± 3.9% and 21.0 ± 5.1% in IH + HIT and normoxia + HIT groups, respectively, P = 0.28). In conclusion, these findings suggest that HIT could represent a preventive strategy to limit IH-induced myocardial ischemia-reperfusion damages in OSA patients.

Effects of High-Intensity Training on Anaerobic and Aerobic Contributions to Total Energy Release During Repeated Supramaximal Exercise in Obese Adults.

BackgroundStudying relative anaerobic and aerobic metabolism contributions to total energy release during exercise may be valuable in understanding exercise energetic demands and the energetic adaptations that occur in response to acute or chronic exercise in obese adults. The aim of the present study is to evaluate the effects of 6 weeks of high-intensity training (HIT) on relative anaerobic and aerobic contributions to total energy release and on peak power output during repeated supramaximal cycling exercises (SCE) in obese adults.MethodsTwenty-four obese adults (body mass index = ± 33 kg.m−2) were randomized into a control group (n = 12) and an HIT group (n = 12). Accumulated oxygen deficits (ml.min−1) and anaerobic and aerobic contributions (%) were measured in all groups before and after training via repeated SCE. In addition, the peak power output performed during SCE was determined using the force-velocity test.ResultsBefore HIT, anaerobic contributions to repeated SCE did not differ between the groups and decreased significantly during the third and fourth repetitions. After HIT, anaerobic contributions increased significantly in the HIT group (+11 %, p < 0.01) and were significantly higher than those of the control group (p < 0.01). Moreover, the peak power obtained during SCE increased significantly in the HIT group (+110 W.kg−1, p < 0.01) and correlated positively with increases in anaerobic contributions (r = 0.9, p < 0.01).ConclusionsIn obese adults, HIT increased anaerobic contributions to energy release which were associated with peak power enhancement in response to repeated SCE. Consequently, HIT may be an appropriate approach for improving energy contributions and muscle power among obese adults.

Predictors of individual adaptation to high-volume or high-intensity endurance training in recreational endurance runners.

The aim of this study was to investigate factors that can predict individual adaptation to high-volume or high-intensity endurance training. After the first 8-week preparation period, 37 recreational endurance runners were matched into the high-volume training group (HVT) and high-intensity training group (HIT). During the next 8-week training period, HVT increased their running training volume and HIT increased training intensity. Endurance performance characteristics, heart rate variability (HRV), and serum hormone concentrations were measured before and after the training periods. While HIT improved peak treadmill running speed (RSpeak ) 3.1 ± 2.8% (P < 0.001), no significant changes occurred in HVT (RSpeak : 0.5 ± 1.9%). However, large individual variation was found in the changes of RSpeak in both groups (HVT: -2.8 to 4.1%; HIT: 0-10.2%). A negative relationship was observed between baseline high-frequency power of HRV (HFPnight ) and the individual changes of RSpeak (r = -0.74, P = 0.006) in HVT and a positive relationship (r = 0.63, P = 0.039) in HIT. Individuals with lower HFP showed greater change of RSpeak in HVT, while individuals with higher HFP responded well in HIT. It is concluded that nocturnal HRV can be used to individualize endurance training in recreational runners.

The effect of training volume and intensity on improvements in muscular strength and size in resistance-trained men.

This investigation compared the effect of high-volume (VOL) versus high-intensity (INT) resistance training on stimulating changes in muscle size and strength in resistance-trained men. Following a 2-week preparatory phase, participants were randomly assigned to either a high-volume (VOL; n = 14, 4 × 10–12 repetitions with ∼70% of one repetition maximum [1RM], 1-min rest intervals) or a high-intensity (INT; n = 15, 4 × 3–5 repetitions with ∼90% of 1RM, 3-min rest intervals) training group for 8 weeks. Pre- and posttraining assessments included lean tissue mass via dual energy x-ray absorptiometry, muscle cross-sectional area and thickness of the vastus lateralis (VL), rectus femoris (RF), pectoralis major, and triceps brachii muscles via ultrasound images, and 1RM strength in the back squat and bench press (BP) exercises. Blood samples were collected at baseline, immediately post, 30 min post, and 60 min postexercise at week 3 (WK3) and week 10 (WK10) to assess the serum testosterone, growth hormone (GH), insulin-like growth factor-1 (IGF1), cortisol, and insulin concentrations. Compared to VOL, greater improvements (P < 0.05) in lean arm mass (5.2 ± 2.9% vs. 2.2 ± 5.6%) and 1RM BP (14.8 ± 9.7% vs. 6.9 ± 9.0%) were observed for INT. Compared to INT, area under the curve analysis revealed greater (P < 0.05) GH and cortisol responses for VOL at WK3 and cortisol only at WK10. Compared to WK3, the GH and cortisol responses were attenuated (P < 0.05) for VOL at WK10, while the IGF1 response was reduced (P < 0.05) for INT. It appears that high-intensity resistance training stimulates greater improvements in some measures of strength and hypertrophy in resistance-trained men during a short-term training period.

Exercise training and Beta-alanine-induced muscle carnosine loading.

Beta-alanine (BA) supplementation has been shown to augment muscle carnosine concentration, thereby promoting high-intensity (HI) exercise performance. Trained muscles of athletes have a higher increase in carnosine concentration after BA supplementation compared to untrained muscles, but it remains to be determined whether this is due to an accumulation of acute exercise effects or to chronic adaptations from prior training. The aim of the present study was to investigate whether high-volume (HV) and/or HI exercise can improve BA-induced carnosine loading in untrained subjects. All participants (n = 28) were supplemented with 6.4 g/day of BA for 23 days. The subjects were allocated to a control group, HV, or HI training group. During the BA supplementation period, the training groups performed nine exercise sessions, consisting of either 75-90 min continuous cycling at 35-45% Wmax (HV) or 3 to 5 repeats of 30 s cycling at 165% Wmax with 4 min recovery (HI). Carnosine content was measured in soleus and gastrocnemius medialis by proton magnetic resonance spectroscopy. There was no difference in absolute increase in carnosine content between the groups in soleus and gastrocnemius muscle. For the average muscle carnosine content, a higher absolute increase was found in HV (+2.95 mM; P = 0.046) and HI (+3.26 mM; P = 0.028) group compared to the control group (+1.91 mM). However, there was no additional difference between the HV and HI training group. HV and HI exercise training showed no significant difference on BA-induced muscle carnosine loading in soleus and gastrocnemius muscle. It can be suggested that there can be a small cumulative effect of exercise on BA supplementation efficiency, although differences did not reach significance on individual muscle level.

A Comparison Study of Short Duration High Intensity Training and Traditional Exercise in Post-Menopausal Women.

The mode and duration of exercise necessary to change body composition and reduce weight remains debatable. Menopause results in hormonal changes that may further impede weight loss. PURPOSE: To compare the effects of short duration, high intensity training (HIT) and traditional methods of exercise (walking) on anthropometric, body composition and body weight changes over a 12-week period. METHODS: Subjects (N=18) were post-menopausal, sedentary female volunteers, randomly assigned into one of two exercise groups. Both groups exercised five out of seven days for 12 weeks. The HIT group (N=8) (54.3±7.3yr; 161.4±13.5lb body wt; BMI=28.0±2.1 kg/m2; mean± SD) exercised for (15.0±3.5 min) which consisted of five different exercise routines including upper and lower extremity, a cardio segment, yoga and abdominal exercises. The walkers (N=10) (56.6±5.2yr; 171.2±15.5lb body wt; BMI=29.2±2.6 kg/m2; mean± SD) exercised for (40.0±5.0 min) at 65% of their age-predicted maximum heart rate. Relative (%) body fat was measured via DEXA scan, along with five anthropometric measurements prior to and after 12 weeks. Independent samples t tests for change were used to probe for significant differences at the p<0.05 level. Values are expressed as mean±standard deviation. RESULTS: No significant changes were determined between the HIT and walking groups for the pre-post anthropometric measurements: biceps, waist, abdomen, hips and thigh (11.9±0.8,12.3±0.8 vs. 12.2±1.2,12.5±0.9; 33.1±3.2,33.6±3.2 vs. 33.2±3.7, 33.2±2.8; 36.4±2.7,37.2±2.2 vs. 36.9±2.8,36.7±2.9; 41.3+1.9,42.2+1.8 vs. 41.1±1.7,41.9±2.3; 25.0±1.4,24.8±1.7 vs. 24.4±1.5, 24.2±1.5 in, respectively). Pre-post relative fat measurements and body weight changes were not significantly different between the HIT and walking groups (45.2±3.3, 43.8±4.7 vs. 44.3±3.7, 43.1±4.8 %fat; 161.6±13.6, 171.2±15.5 vs.159.9±14.8, 168.6±15.2 lb, respectively). CONCLUSION: No differences were observed between short duration HIT exercise group and the traditional exercise group (walking) on anthropometric measures, relative percent body fat and body weight over a 12-week period. This work is suggestive that the mode of exercise did not impact pre-post measures for change between a HIT program and a traditional walking exercise program.

Effects Of Isocaloric Aerobic Training With Different Intensities Upon Fitness, Adiposity And Microcirculation In Rats

BACKGROUND: The role of exercise intensity and volume within aerobic training to improve cardiovascular and metabolic markers remains unclear. PURPOSE: To investigate the effects of isocaloric aerobic training performed with different intensities upon body composition, cardiorespiratory fitness and endothelial-dependent vasodilation in eutrophic rats. METHODS: Wistar rats (n=30) were assigned into three groups: sedentary control (SC), high-intensity training (HI), and moderate-intensity training (MI). MI and HI groups performed treadmill running for 4 weeks at speeds corresponding to 50% and 80% oxygen uptake reserve (VO2R), respectively. The duration of exercise sessions was controlled through energy expenditure (MI=3.4±0.3, HI=3.2±0.3 kcal; P=0.61). At the end of intervention all groups had assessed the body composition (DEXA), cardiorespiratory fitness (VO2max), and endothelial-dependent vasodilation (intravital microscopy). RESULTS: Only HI presented lower fat mass (101.2±3.0 g vs. 124.8±2.0 g; P=0.01) and % fat (29.8±1.0% vs. 35.5±1.0%; P=0.03) compared to SC after training. The VO2max increased in both exercised groups vs. SC (P<0.001), but improvement was higher in HI over MI (P<0.001) (ΔSC= -3.7±3.0 ml.kg-1.min-1; ΔHI= 4.9±2.0 ml.kg-1.min-1; ΔMI= 2.5±3.0 ml.kg-1.min-1). Endothelial-dependent vasodilation in response to acetylcholine improved similarly in HI and MI (21.5% vs. 20.8%; P=0.73) vs. SC (P<0.05). CONCLUSION: Isocaloric aerobic training with high-intensity was more effective to improve adiposity and cardiorespiratory fitness in eutrophic rats. On the other hand, endothelial function improved similarly in both exercise groups, suggesting that energy expenditure would be more important than exercise intensity to enhance endothelial-dependent vasodilation. Supported by the Brazilian Council for the Technological and Research Development (CNPq) and Carlos Chagas Foundation for the Research Development in the State of Rio de Janeiro (FAPERJ).

Effect of the low- versus high-intensity exercise training on endoplasmic reticulum stress and GLP-1 in adolescents with type 2 diabetes mellitus.

[Purpose] The primary objective of this study was to investigate the effect of low-intensity exercise training compare with high-intensity exercise training on endoplasmic reticulum stress and glucagon-like peptide-1 in adolescents with type 2 diabetes mellitus. [Subjects and Methods] The low-intensity exercise training group performed aerobic exercise training at an intensity of ≤ 45% of the heart rate reserve. The high-intensity interval exercise training group performed interval exercise training at an intensity of ≥ 80% of the heart rate reserve. The exercise-related energy consumption was determined for both groups on a per-week basis (1,200 kcal/week). [Results] Both groups showed improvement in the glucose-regulated protein 78 and dipeptidyl peptidase-4, but the size of the between-group effect was not statistically significant. The high-intensity interval exercise training group showed a significant reduction in percentage body fat. The C-peptide level increased after the 12-weeks programs and was significantly different, between the groups. Fasting glucose, insulin resistance in the fasting state according to homeostasis model assessment, and leptin decreased after the 12-weeks exercise program and were significantly different between the groups, and glucagon-like peptide-1 increased after the 12-week exercise programs and was significantly different between the groups. [Conclusion] In conclusion high-intensity interval exercise training, as defined in this study, may lead to improvements in body composition, glycemic control, endoplasmic reticulum stress, and the glucagon-like peptide-1 in adolescents with type 2 diabetes mellitus.

The effect of progressive high-intensity inspiratory muscle training and fixed high-intensity inspiratory muscle training on the asymmetry of diaphragm thickness in stroke patients.

[Purpose] This study investigated the effects of progressive load and fixed load high-intensity inspiratory muscle training on the asymmetry of diaphragm thickness in stroke patients. [Subjects] Twenty-one stroke patients were assigned to one of three groups: progressive load high-intensity inspiratory muscle training (n = 8), fixed load high-intensity inspiratory muscle training (n = 6), and controls (n = 7). [Methods] The progressive load and fixed load high-intensity inspiratory muscle training participants undertook an exercise program for 20 minutes, three times weekly, for 6 weeks. After each session, diaphragm thickness was measured using ultrasonography. The diaphragm asymmetry ratio and diaphragm thickening ratio were standardized using a formula. [Results] After intervention, the diaphragm asymmetry ratio significantly differed among the three groups, and the diaphragm asymmetry ratio significantly increased in the control group. A significant increase was identified in the diaphragm thickening ratio within the progressive load and fixed load high-intensity inspiratory muscle training groups. [Conclusion] Progressive load and fixed load high-intensity inspiratory muscle training decreased the asymmetry of diaphragm thickness in stroke patients; this effect, in turn, increased the diaphragm thickening ratio in stroke patients. The two interventions examined here should be selectively applied to individuals in the clinical field.

Chronic exercise increases plasma brain-derived neurotrophic factor levels, pancreatic islet size, and insulin tolerance in a TrkB-dependent manner.

BackgroundPhysical exercise improves glucose metabolism and insulin sensitivity. Brain-derived neurotrophic factor (BDNF) enhances insulin activity in diabetic rodents. Because physical exercise modifies BDNF production, this study aimed to investigate the effects of chronic exercise on plasma BDNF levels and the possible effects on insulin tolerance modification in healthy rats.MethodsWistar rats were divided into five groups: control (sedentary, C); moderate- intensity training (MIT); MIT plus K252A TrkB blocker (MITK); high-intensity training (HIT); and HIT plus K252a (HITK). Training comprised 8 weeks of treadmill running. Plasma BDNF levels (ELISA assay), glucose tolerance, insulin tolerance, and immunohistochemistry for insulin and the pancreatic islet area were evaluated in all groups. In addition, Bdnf mRNA expression in the skeletal muscle was measured.Principal FindingsChronic treadmill exercise significantly increased plasma BDNF levels and insulin tolerance, and both effects were attenuated by TrkB blocking. In the MIT and HIT groups, a significant TrkB-dependent pancreatic islet enlargement was observed. MIT rats exhibited increased liver glycogen levels following insulin administration in a TrkB-independent manner.Conclusions/SignificanceChronic physical exercise exerted remarkable effects on insulin regulation by inducing significant increases in the pancreatic islet size and insulin sensitivity in a TrkB-dependent manner. A threshold for the induction of BNDF in response to physical exercise exists in certain muscle groups. To the best of our knowledge, these are the first results to reveal a role for TrkB in the chronic exercise-mediated insulin regulation in healthy rats.

Effects of High-intensity Intermittent Training and Moderate-intensity Training on Cardiopulmonary Capacity in Canoe and Kayak Paddlers during 8 Weeks

PURPOSE: The purpose of this study was to investigate the effects of high intensity intermittent training on cardiopulmonary capacity in canoe and kayak paddlers. METHODS: A total of 16 canoe and kayak paddlers were participated in this study. Experimental group(n=8) was performed high-intensity intermittent training and control group(n=8) was moderate intensity training. All subjects performed a treadmill test in order to compare the difference before and after the intervention. Finishing the test, all subjects were measured to their heart rate(HR), forced vital capacity(FVC), forced expiratory volume in one second (FEV1) and forced expiratory ratio(FEV1/FVC). Recovery of heart rate(RHR) was calculated using the HR. HR and pulmonary flow values was measured before and during the intervention period per 2, 4, 6 and 8 weeks. To compare the differences over time between experimental group and the control group, used(time<TEX>${\times}$</TEX>group) two-way repeated measures ANOVA. One-way repeated ANOVA was performed to determine where differences over time within-group. RESULTS: One-way repeated ANOVA revealed a significant difference in the experimental and control group. In experimental group, %RHR3min and FEV1 were significantly increased after 4 weeks(p<.05). Also, %RHR1min, FVC and FEV1/FVC were significantly increased after 6 weeks(p<.05). In control group, %RHR1min, %RHR3min, FVC, FEV1 and FEV1/FVC were significantly increased after 6 weeks(p<.05). CONCLUSION: Not only moderate training but also high-intensity intermittent training contributes to cardiopulmonary capacity in canoe and kayak paddlers. Although high-intensity intermittent training is very short time, the training has high degree of efficiency. Therefore, developed this training in the future, it will be better to improve the cardiopulmonary capacity for athletes and healthy people.

High intensity training improves health and physical function in middle aged adults.

High intensity training (HIT) is effective at improving health; however, it is unknown whether HIT also improves physical function. This study aimed to determine whether HIT improves metabolic health and physical function in untrained middle aged individuals. Fourteen (three male and eleven female) untrained individuals were recruited (control group n = 6: age 42 ± 8 y, weight 64 ± 10 kg, BMI 24 ± 2 kg·m−2 or HIT group n = 8: age 43 ± 8 y, weight 80 ± 8 kg, BMI 29 ± 5 kg·m−2). Training was performed twice weekly, consisting of 10 × 6-second sprints with a one minute recovery between each sprint. Metabolic health (oral glucose tolerance test), aerobic capacity (incremental time to exhaustion on a cycle ergometer) and physical function (get up and go test, sit to stand test and loaded 50 m walk) were determined before and after training. Following eight weeks of HIT there was a significant improvement in aerobic capacity (8% increase in VO2 peak; p < 0.001), physical function (11%–27% respectively; p < 0.05) and a reduction in blood glucose area under the curve (6% reduction; p < 0.05). This study demonstrates for the first time the potential of HIT as a training intervention to improve skeletal muscle function and glucose clearance as we age.

Effect of aerobic training on insulin resistance and C-reactive protein (CRP) levels and subcutaneous abdominal in obese women

This study examined the effect of three training intensities on abdominal obesity, insulin resistance, and C-reactive protein (CRP) levels. Forty-three young obese women (age 20–30 years; body mass index 30–40 kg/m2) underwent 12 weeks of walking programs (i.e., 5 days/week). They were randomly assigned to one of four groups: low-intensity training group [G1, 50 % of heart rate reserve (HRR), n = 11], high-intensity training group (G2, 75 % of HRR, n = 10), alternated-intensity training group (G3, 50–75 % of HRR, n = 12), and control group (G0, n = 10). They were tested before (T0) and after (T1) 12 weeks of aerobic training to determine changes in body mass, body mass index (BMI), total fat, waist circumference (WC), leptin, HOMA-IR, glucose and CRP. Body mass, BMI, total fat, and WC were significantly lower at T1 than T0 (p < 0.001) in all training groups. However, the decrease was higher in G2 than G1 and G3. Leptin levels decreased significantly in G1, G2, and G3 (p < 0.05). Only G1 showed significant decreases in CRP levels (p < 0.05). Insulin, HOMA-IR, and glucose levels decreased in the three training groups with higher decrease in G1. The low-intensity training is more effective than the high-intensity training or alternated-intensity training for improving insulin sensitivity and reducing subclinical inflammation.