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PURPOSE This study aimed to compare body composition, physical fitness, maximum muscle strength, and blood lactate concentration according to the level of aerobic capacity in Keirin cyclists. METHODS Forty-four Keirin cyclists participated in this study and were divided into three groups: the top 20% VO2max group (TG, n=9), the middle 20% VO2max group (MG, n=9), and the low 20% VO2max group (LG, n=9). The study measured body composition, physical fitness, maximum muscle strength, and blood lactate concentration in Keirin cyclists. Differences between groups were determined using one-way ANOVA analysis. RESULTS Body weight, percentage of body fat, and body mass index were significantly higher in the LG than in the TG and MG. The vertical jump and maximum muscle strength were significantly higher in the TG and MG than in the LG. Additionally, blood lactate concentrations immediately after exhaustive exercise and during the 5-minute recovery periods were higher in the LG than in the TG and MG. Moreover, the time to exhaustion, HRmax and maximum power were the highest in the TG. CONCLUSIONS Our findings suggest new information that levels of aerobic capacity in male Keirin cyclists might be a crucial predictor of cycling performance and recovery ability.

Relevance. Сardiovascular status could be assessed by maximal aerobic capacity (VO2max) through direct analysis of the gases involved in pulmonary ventilation and monitoring fluctuations in intervals between beats over time as heart rate variability. The aim of the study was to investigate the relationship between VO2max and heart rate variability in young adults. Materials and Methods. A total of 100 young adults between the ages of 18 and 25 were included in observational study, who did not engage in any strenuous physical activity, 50 of whom were male and 50 of whom were female.There were measured Heart rate variability in the frequency domain; LF, HF, LF/HF, and time domain; SDNN, RMSSD, pNN 50, and VO2max were assessed using a treadmill test according to Graded Exercise Protocol. Results and Discussion. There was weak positive correlation of VO2max with LF ( r = 0.177) and weak negative correlation with HF ( r = -0.141). Male participants had a weak negative relationship between VO2 max and LF ( r = -0.075), whereas female respondents had a weak positive relationship(r = 0.286). There was weak negative correlation of VO2max with LF/HF ratio for male subjects but weak positive correlation ( r = -0.101) for female subjects. For male and female participants, there was a weak negative association of VO2max with SDNN ( r = -0.170) and ( r = -0.301), respectively. Male and female participants had a weak negative association of VO2max with RMSSD, with ( r = -0.154) and ( r = -0.284) respectively. Male and female participants had a slight negative association of VO2max with pNN 50, with ( r = -0.062) and ( r = -0.441) respectively. Conclusion. Significant variations were found in the time domain and frequency domain indices including HF and LF/HF ratio which represents the balance between sympathetic and parasympathetic responses.

PURPOSE To assess the agreement between maximal oxygen consumption (VO2max) measured directly when performing the maximal graded exercise test (GXT) and estimated VO2max from two different equations in Korean male and female youths aged 13-18 years. METHODS Sixty-six adolescents (15.3±1.7 years, 166.0±7.8 cm, 58. 7±10.0 kg, BMI 21.2±2.7) performed GXT on a treadmill and Astrand-Ryhming step test (AR test) to measure VO2max and VO2max estimates, respectively. The participants wore a portable device (Polar CS300) to measure heart rate (HR) during the tests. RESULTS Correlation coefficients (r) between VO2max of the equations and VO2max of the measured value were 0.321 (p

PURPOSE To develop and validate regression models to estimate maximal oxygen uptake (VO2max) from the new estimation formula based on Astrand-Ryhming step test protocol (AR protocol) in Korean male and female youths aged 13-18 years. METHODS One hundred twenty participants performed maximal graded exercise test (GXT) on a treadmill and Astrand-Ryhming step test (AR test) to measure VO2max and VO2max estimates, respectively. Participants in the validation study performed the GXT with the stationary metabolic cart and the Astrand-Ryhming step test twice for test-retest reliability. All tests were conducted at least three days apart and in a random order. RESULTS Mean calculated VO2max (40.43±11.57 mL/kg/min) from the Astrand-Ryhming step test equation was significantly low from that measured during the GXT from stationary metabolic cart (47.32±8.75 mL/kg/min, p

PURPOSE To develop and validate regression models to estimate maximal oxygen uptake (VO2max) from the new 20-m Progressive Shuttle Test (20-m PST) in Korean male youths aged 13-18 years. METHODS The new 20-m PST and VO2max were assessed in a sample of 80 participants. Participants underwent a treadmill test (TT) in the laboratory and the new 20-m PST protocol (starting at 5.0 km/h and increasing by 0.75 km/h every 1 minute) in a gymnasium. Participants in the validation study performed the TT with the stationary metabolic cart and the 20-m PST with a portable metabolic cart once, as well as the 20-m PST without the portable metabolic cart twice for test-retest reliability. All tests were conducted at least three days apart and in a random order. RESULTS Mean measured VO2max (55.4±6.7 mL/kg/min) from the potable metabolic cart was significantly increased from that measured during the GXT from stationary metabolic cart (52.6±7.0 mL/kg/min, p=.001) using the new 20-m PST protocol. But it was a narrow range (2.8 mL/kg/min). The measured VO2max from the potable and stationary metabolic cart correlated at r=.89 (p

Purpose: To determine whether maximal oxygen uptake (VOmax) could be predicted accurately and reliably from a 2-step, perceptually-regulated exercise test (PRET) in healthy adults. Methods: Sixteen participants (31.7 ± 11.3 years, 3 females) completed three PRETs (separated by 24-72 h) and one maximal, perceptually-regulated, graded exercise test (PRETmax) on a motorized treadmill. Oxygen uptake (VO) and heart rate (HR) were recorded during each test. VO values for RPE range 9-15 were extrapolated to RPE 20 and age-predicted maximal HR (HRmax) using individual linear regression analysis to predict VOmax values compared to measured VOmax. Results: VO and HR values were consistent between each of four RPE levels of the PRET. ICC values ranged between 0.76 and 0.85. Predicted VOmax from both methods were lower than measured VOmax ( p < 0.01). Limits of agreement (LoA) for measured (41.4 ± 5.3 ml kg min) versus predicted VOmax from each of the three PRETs using RPE20 were −1.2 ± 15.6, −1.0 ± 7.2 and −2.1 ± 5.5 and for HRmax were −1.8 ± 4.2; −2.6 ± 4.2 and −2.4 ± 4.4 ml kg min for PRET 1, 2 and 3, respectively. Conclusions: The step PRET elicited significant and reliable increases in VO across the four RPE levels, but under-estimated treadmill VOmax. However, there was better agreement between measured and predicted VOmax when extrapolated to HRmax. As evidence indicates the underestimation of VOmax is explained by the difference in the mode of exercise, the step PRET provides a simple and convenient test of cardiorespiratory fitness. [ABSTRACT FROM AUTHOR]

The aim of the present study was to determine whether low-level laser therapy (LLLT), when used in conjunction with aerobic training, interferes with the expression of inflammatory markers IL-6 and TNF-α, thereby influencing the performance of old rats participating in swimming. A total of 30 Wistar rats ( Rattus norvegicus albinus) were used for this study: 24 aged rats, and 6 young rats. The older animals were randomly divided into four groups designated as follows: aged-control, aged-exercise, aged-LLLT, aged-LLLT/exercise group, and young-control animals. Aerobic capacity (VOmax) was analyzed before and after training period. The aged-exercise and aged-LLLT/exercise groups were trained for 6 weeks. LLLT laser was applied before each training session with 808 nm and 4 J of energy to the indicated groups throughout training. The rats were euthanized, and muscle tissue and serum were collected for muscle cross-sectional area and IL-6 and TNF-α protein analysis. In VO2 showed statistical difference between young- and aged-control groups (used as baseline) ( p < 0.05). The same difference can be observed in the young control group compared with all intervention groups (exercise, LLLT and LLLT + exercise). In comparison with the aged-control group, a difference was observed only for comparison with the exercise group ( p < 0.05), and exercise associated with LLLT group ( p < 0.001). Levels of IL-6 and TNF-α for the aged-exercise and the aged-LLLT/exercise groups were significantly decreased compared to the aged-control group ( p < 0.05). Analysis of the transverse section of the gastrocnemius muscle showed a significant difference between the aged-exercise and aged-LLLT/exercise groups ( p < 0.001). These results suggest that laser therapy in conjunction with aerobic training may provide a therapeutic approach for reducing the inflammatory markers (IL-6 and TNF-α), however, LLLT without exercise was not able to improve physical performance of aged rats. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effect of an exercise training program combining low-impact dance aerobic, resistance and stretching exercise on physical fitness, hormone and lipid levels of postpartum, primiparous, lactating women. Methods: Thirty seven primiparous, lactating women were randomly assigned at 4−6 weeks postpartum to either follow an exercise training program of 50−60 min aerobic, strengthening and stretching exercise, 3 days a week, for 12 weeks (interventional group; n = 20) or no training program at all (control group; n = 17). The following parameters were measured at baseline and 12 weeks later: (1) for evaluation of physical fitness: VOmax, muscular endurance, joint mobility and body fat; (2) for evaluation of the lipidemic profile: triglyceride, total cholesterol, HDL and LDL levels, and (3) levels of hormones associated with lactation: prolactin, estradiol, cortisol, TSH, fT3 and fT4. Results: After completion of the exercise training program, comparisons between the interventional and the control group showed statistically significant mean changes in VOmax ( p = 0.003), muscular endurance of the upper extremities ( p < 0.001), and the abdomen ( p < 0.001), flexibility ( p = 0.042), and body fat ( p = 0.007). There were no significant differences between the two groups in mean changes of lipid and hormone levels. Conclusion: Implementation of a low-impact exercise training program appears to improve physical fitness of postpartum women, while it does not seem to affect lipid levels and lactation-associated hormone levels. Hence, implementation of an exercise training program combining low-impact dance aerobic, resistance and stretching exercise is feasible in postpartum, primiparous, lactating women. [ABSTRACT FROM AUTHOR]

Evidence suggests that serum brain-derived neurotrophic factor (serum BDNF) can be affected by cardiorespiratory fitness (CRF), but this relationship is far from clear. Recent reports show an inverse relationship between serum BDNF and CRF in healthy individuals, and other studies suggest a possible association between serum BDNF and cardiovascular disease. However, the possible interaction between serum BDNF, CRF, and cardiovascular disease risk has not been studied. The purpose of this study was to examine the association among serum BDNF, CRF, and cardiovascular disease risk factors in healthy men. The investigation involved a large sample of men (n = 995, age range: 20-76 years) who live in the central area of South Korea and were recruited into the Preventive Health Study. Our study showed a significant inverse relationship between serum BDNF and relative VO(2)max (r = -0.412, p < 0.0001) and heart rate reserve (r = -0.194, p < 0.0001). Serum BDNF was positively correlated with body mass index (r = 0.80, p < 0.0001), total cholesterol (r = 0.185, p < 0.0001), and triglyceride (r = 0.320, p < 0.0001). Our data suggest that serum BDNF may be associated with effects of increased CRF on cardiovascular disease. However, more research is clearly needed before a determination of whether, and to what extent, serum BDNF may be responsible for some of the health benefits associated with CRF. [ABSTRACT FROM AUTHOR]

Bacteria residing in the human gastrointestinal tract has a symbiotic relationship with its host. Animal models have demonstrated a relationship between exercise and gut microbiota composition. This was the first study to explore the relationship between cardiorespiratory fitness (maximal oxygen consumption, VO 2 max) and relative gut microbiota composition (Firmicutes to Bacteroidetes ratio [F/B]) in healthy young adults in a free-living environment. Twenty males and 17 females (25.7 ± 2.2 years), who did not take antibiotics in the last 6 months, volunteered for this study. VO 2 max was measured using a symptom-limited graded treadmill test. Relative microbiota composition was determined by analyzing DNA extracted from stool samples using a quantitative polymerase chain reaction that specifically measured the quantity of a target gene (16S rRNA) found in Firmicutes and Bacteroidetes. Relationships between F/B and potentially related dietary, anthropometric, and fitness variables were assessed using correlation analyses with an appropriate Bonferroni adjustment ( p  < .004). The average F/B ratio in all participants was 0.94 ± 0.03. The F/B ratio was significantly correlated to VO 2 max ( r  = .48, p  < .003), but no other fitness, nutritional intake, or anthropometric variables ( p  > .004). VO 2 max explained ∼22% of the variance of an individual's relative gut bacteria as determined by the F/B ratio. These data support animal findings, demonstrating a relationship between relative human gut microbiota composition and cardiorespiratory fitness in healthy young adults. Gastrointestinal bacteria is integral in regulating a myriad of physiological processes, and greater insight regarding ramifications of exercise and nutrition on gut microbial composition may help guide therapies to promote human health.

Purpose: To investigate changes in physiological and performance variables in triathletes following a 4-wk period of reduced training volume and increased training intensity., Methods: Sixteen moderately trained triathletes were randomly allocated to 2 groups: a control (CON) group, which followed their usual training, or a high-intensity interval training (HIIT) group, which completed 2 HIIT sessions per week during 4 wk of reduced training volume Results: Maximal oxygen consumption (VO 2 max) increased significantly in the HIIT group (P = .03, d = 0.5) but remained unchanged in the CON group. Cycling power at first and second ventilatory thresholds increased significantly in the HIIT subjects (P = .03, d = 1.0) and was unchanged in the CON participants (P = .57). During the simulated triathlon test, pretest-posttest cycling times and average power were unchanged in both groups (P > .05). No significant interactive effects between groups were observed for running time (P = .50)., Conclusion: After a 4-wk HIIT program, VO 2 max and power at first and second ventilatory thresholds were found to have increased significantly while cycling and running performance were unchanged, despite an overall reduction in training time. In the present study, performance was only shown to improve with usual (high-volume) training. Summarizing, in order to improve running or cycling performances, high-volume training programs are highly recommended.