Effects of various interval training regimes on changes in maximal oxygen uptake, body composition, and muscular strength in sedentary women with obesity.

PURPOSE: We determined the effects of two high-intensity interval training (HIIT) regimens [the traditional (TRAD) and periodized (PER)] on changes in maximal oxygen uptake (VO2max), body composition, and muscular strength in sedentary, obese women. METHODS: Seventeen women (age and BMI = 37.5 ± 10.5 year and 39.1 ± 4.3 kg/m2) were randomized into a 6 week regime of TRAD or PER which consisted of three sessions per week, two in the laboratory, and one on their own. Pre- and post-training, VO2max, body composition, and muscular strength of the knee extensors (KE) and flexors (KF) were assessed via ramp cycling to exhaustion, air displacement plethysmography, and isokinetic dynamometry, respectively. RESULTS: VO2max was increased by 4-5% in response to training (p = 0.045) with no group-by-time interaction (p = 0.79). Body mass, fat mass, and waist-to-hip ratio were unaltered (p > 0.05) in response to training, yet there was a significant change in percent body fat (p = 0.03), percent fat-free mass (p = 0.03), and absolute fat-free mass (p = 0.03) in TRAD but not PER. No change occurred in KE (p = 0.36) or KF torque (p = 0.75) in response to training and there was no group-by-time interaction (p > 0.05). CONCLUSIONS: Low-volume HIIT improved VO2max and body composition but did not modify muscular strength, which suggests that obese women desiring to increase strength should initiate more intense HIIT or partake in formal resistance training.

Change in VO2max and time trial performance in response to high-intensity interval training prescribed using ventilatory threshold.

Completion of high-intensity interval training (HIIT) leads to significant increases in maximal oxygen uptake (VO2max) and oxidative capacity. However, individual responses to HIIT have been identified as approximately 20-40% of individuals show no change in VO2max, which may be due to the relatively homogeneous approach to implementing HIIT. PURPOSE: This study tested the effects of HIIT prescribed using ventilatory threshold (VT) on changes in VO2max and cycling performance. METHODS: Fourteen active men and women (age and VO2max = 27 ± 8 year and 38 ± 4 mL/kg/min) underwent nine sessions of HIIT, and 14 additional men and women (age and VO2max = 22 ± 3 year and 40 ± 5 mL/kg/min) served as controls. Training was performed on a cycle ergometer at a work rate equal to 130%VT and consisted of eight to ten 1 min bouts interspersed with 75 s of recovery. At baseline and post-testing, they completed progressive cycling to exhaustion to determine VO2max, and on a separate day, a 5 mile cycling time trial. RESULTS: Compared to the control group, HIIT led to significant increases in VO2max (6%, p = 0.007), cycling performance (2.5%, p = 0.003), and absolute VT (9 W, p = 0.005). However, only 57% of participants revealed meaningful increases in VO2max and cycling performance in response to training, and two showed no change in either outcome. CONCLUSIONS: A greater volume of HIIT may be needed to maximize the training response for all individuals.

Assessment and application of the Bunkie test in college students.

INTRODUCTION: The 'Bunkie test' is a functional performance test consisting of five different plank positions held bilaterally. No current literature has established appropriate rest intervals for in-between plank positions nor termination criteria. PURPOSE: The current study examined rest interval duration and test termination criteria for the Bunkie test. METHODS: Forty college students participated in the study, completing three Bunkie test sessions separated by at least 48 h. Positions included the anterior power line (APL), lateral stabilizing line (LSL), posterior power line (PPL), posterior stabilizing line (PSL), and medial stabilizing line (MSL). Positions were held for as long as possible with proper form. Each session utilized a different rest interval of either 30s, 1min, or 2min between each of the plank positions. RESULTS: A repeated measures ANOVA revealed significant differences bilaterally among rest intervals for APL (p = .009; p = .001) whereas, no significant differences (p < .05) were observed for PPL. LSL and MSL and PSL had significant differences among rest intervals on one side (LSL left, p = .002; MSL right, p = .006; PSL right p=.005)). Post hoc analysis with a Bonferroni adjustment revealed less variability among times between the 1min and 2min rest intervals between plank positions. CONCLUSIONS: The current study revealed that utilizing a shorter rest interval time frame (30s) appears to create greater variability in performance outcomes. Since no differences were found between using a 1min or 2min rest interval for both the final hold times and tension times, a rest interval of at least 1min will allow for more dependable data.

Blood Lactate Concentration Is Not Related to the Increase in Cardiorespiratory Fitness Induced by High Intensity Interval Training.

BACKGROUND: There is individual responsiveness to exercise training as not all individuals experience increases in maximal oxygen uptake (VO2max), which does not benefit health status considering the association between VO2max and mortality. Approximately 50% of the training response is genetic, with the other 50% accounted for by variations in dietary intake, sleep, recovery, and the metabolic stress of training. This study examined if the blood lactate (BLa) response to high intensity interval training (HIIT) as well as habitual dietary intake and sleep duration are associated with the resultant change in VO2max (ΔVO2max). METHODS: Fourteen individuals (age and VO2max = 27 ± 8 years and 38 ± 4 mL/kg/min, respectively) performed nine sessions of HIIT at 130% ventilatory threshold. BLa was measured during the first and last session of training. In addition, sleep duration and energy intake were assessed. RESULTS: Data showed that VO2max increased with HIIT (p = 0.007). No associations occurred between ΔVO2max and BLa (r = 0.44, p = 0.10), energy intake (r = 0.38, p = 0.18), or sleep duration (r = 0.14, p = 0.62). However, there was a significant association between training heart rate (HR) and ΔVO2max (r = 0.62, p = 0.02). CONCLUSIONS: When HIIT is prescribed according to a metabolic threshold, energy intake, sleep status, and BLa do not predict ΔVO2max, yet the HR response to training is associated with the ΔVO2max.

Efficacy of constant load verification testing to confirm VO2 max attainment.

Although maximal oxygen uptake (VO2 max) has been measured for almost 100 years, it is unknown when 'true' VO2 max is attained. Primary (the VO2 plateau) and secondary criteria are used to confirm VO2 max incidence, but frequency of the VO2 plateau varies, and secondary criteria are relatively invalid. The verification test (VER) seems to elicit similar estimates of VO2 max versus the incremental value (INC), yet existing data are limited by small populations and use of inadequate criteria to confirm 'true' VO2 max. We investigated the efficacy of VER by analysing data from 109 participants who underwent INC followed by VER at 105% or 110% of peak power output (PPO). Differences in VO2 max between VER and INC were analysed, and intraclass correlation coefficient (ICC), standard error of the mean (SEM) and minimum difference (MD) were computed. Results showed that VO2 max was significantly higher (2%, P<0·05) in INC versus VER, VO2 max was highly related between protocols (ICC = 0·99) and SEM and MD were low. However, 11% of participants did not reveal 'true' VO2 max as the verification value was higher than INC by 3·0% - 3·3%. Fitness level altered the difference in VO2 max between INC and VER in study one, as lower fitness individuals showed a larger difference in VO2 max between protocols, although gender did not affect the difference in VO2 max between protocols. Our data show that VER does not verify 'true' VO2 max in all individuals, which may be related to their fitness level.