Creatine Monohydrate Supplementation Does Not Augment Fitness, Performance, or Body Composition Adaptations in Response to Four Weeks of High-Intensity Interval Training in Young Females

2017 ◽  
Vol 27 (3) ◽  
pp. 285-292 ◽  
Author(s):  
Scott C. Forbes ◽  
Nathan Sletten ◽  
Cody Durrer ◽  
Étienne Myette-Côté ◽  
D. Candow ◽  
...  

High-intensity interval training (HIIT) has been shown to improve cardiorespiratory fitness, performance, body composition, and insulin sensitivity. Creatine (Cr) supplementation may augment responses to HIIT, leading to even greater physiological adaptations. The purpose of this study was to determine the effects of 4 weeks of HIIT (three sessions/week) combined with Cr supplementation in recreationally active females. Seventeen females (age = 23 ± 4 yrs; BMI = 23.4 ± 2.4) were randomly assigned to either Cr (Cr; 0.3 g・kg-1・d-1 for 5 d followed by 0.1 g・kg-1・d-1 for 23 days; n = 9) or placebo (PLA; n = 8). Before and after the intervention, VO2peak, ventilatory threshold (VT), time-trial performance, lean body mass and fat mass, and insulin sensitivity were assessed. HIIT improved VO2peak (Cr = +10.2%; PLA = +8.8%), VT (Cr = +12.7%; PLA = +9.9%), and time-trial performance (Cr = -11.5%; PLA = -11.6%) with no differences between groups (time main effects, all p < .001). There were no changes over time for fat mass (Cr = -0.3%; PLA = +4.3%), whole-body lean mass (Cr = +0.5%; PLA = -0.9%), or insulin resistance (Cr = +3.9%; PLA = +18.7%). In conclusion, HIIT is an effective way to improve cardiorespiratory fitness, VT, and time-trial performance. The addition of Cr to HIIT did not augment improvements in cardiorespiratory fitness, performance or body composition in recreationally active females.

2017 ◽  
Vol 6 (2) ◽  
pp. 27-33
Author(s):  
BAHAR ATEŞ ◽  
Ebru ÇETİN

The purpose of this study was to investigate the 8-week of roller-ski aerobic high-intensity interval training on aerobic and anaerobic power in cross-country skiers. 10 male [age, 18,28±2,1 years; height, 171,26±4,12 cm; weight, 61,39±6,28 kg] and 8 female [age, 16,05±0.3 years; height, 158,3±6,47 cm; weight, 49,34±0.7 kg]  junior cross-country skiers completed the study. All skiers performed 2x2-km all-out uphill intervals with roller-skis, 3 times a week, in addition to their traditional training program. Measurements included VO2max, anaerobic power, and also for 2-km time-trial performance. All values were listed as pre-to post-test mean [±SD], significant level, and percentage changes [%]. Pre-to post-testing changes in VO2max, anaerobic power, and also 2-km time-trial performance were significantly higher during all post-test trials in all groups [p<0.005]. As a result, we suggest that the skiers should integrate the roller-ski aerobic high-intensity interval uphill models in their training programs for improving performance.


Author(s):  
Mark A. Faghy ◽  
Peter I. Brown ◽  
Nicola M. Davis ◽  
J. P. Mayes ◽  
Tom M. Maden-Wilkinson

Abstract Purpose There is little evidence of the ergogenic effect of flow-resistive masks worn during exercise. We compared a flow-resistive face mask (MASK) worn during high-intensity interval training (HIIT) against pressure threshold loading inspiratory muscle training (IMT). Methods 23 participants (13 males) completed a 5 km time trial and six weeks of HIIT (3 sessions weekly). HIIT (n = 8) consisted of repeated work (2 min) at the speed equivalent to 95% $${\dot{\text{V}}}$$ V ˙ O2 peak with equal rest. Repetitions were incremental (six in weeks 1, 2 and 6, eight in weeks 3 and 4 and ten in week 5). Participants were allocated to one of three training groups. MASK (n = 8) wore a flow-resistive mask during all sessions. The IMT group (n = 8) completed 2 × 30 breaths daily at 50% maximum inspiratory pressure (PImax). A control group (CON, n = 7) completed HIIT only. Following HIIT, participants completed two 5 km time trials, the first matched identically to pre-intervention trial (ISO time), and a self-paced effort. Results Time trial performance was improved in all groups (MASK 3.1 ± 1.7%, IMT, 5.7 ± 1.5% and CON 2.6 ± 1.0%, p < 0.05). IMT improved greater than MASK and CON (p = 0.004). Post intervention, PImax and diaphragm thickness were improved in IMT only (32% and 9.5%, respectively, p = 0.003 and 0.024). Conclusion A flow-resistive mask worn during HIIT provides no benefit to 5 km performance when compared to HIIT only. Supplementing HIIT with IMT improves respiratory muscle strength, morphology and performance greater than HIIT alone.


2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Zhaowei Kong ◽  
Shengyan Sun ◽  
Min Liu ◽  
Qingde Shi

This study was to determine the effects of five-week high-intensity interval training (HIIT) on cardiorespiratory fitness, body composition, blood glucose, and relevant systemic hormones when compared to moderate-intensity continuous training (MICT) in overweight and obese young women.Methods. Eighteen subjects completed 20 sessions of HIIT or MICT for five weeks. HIIT involved 60 × 8 s cycling at ~90% of peak oxygen consumption (V˙O2peak) interspersed with 12 s recovery, whereas MICT involved 40-minute continuous cycling at 65% ofV˙O2peak.V˙O2peak, body composition, blood glucose, and fasting serum hormones, including leptin, growth hormone, testosterone, cortisol, and fibroblast growth factor 21, were measured before and after training.Results. Both exercise groups achieved significant improvements inV˙O2peak(+7.9% in HIIT versus +11.7% in MICT) and peak power output (+13.8% in HIIT versus +21.9% in MICT) despite no training effects on body composition or the relevant systemic hormones. Blood glucose tended to be decreased after the intervention (p=0.062). The rating of perceived exertion in MICT was higher than that in HIIT (p=0.042).Conclusion. Compared with MICT, short-term HIIT is more time-efficient and is perceived as being easier for improving cardiorespiratory fitness and fasting blood glucose for overweight and obese young women.


2021 ◽  
Vol 8 ◽  
Author(s):  
Lukas Cipryan ◽  
Tomas Dostal ◽  
Martina Litschmannova ◽  
Peter Hofmann ◽  
Philip B. Maffetone ◽  
...  

Purpose: This randomized controlled parallel-group study examined the effects of a very low-carbohydrate high-fat (VLCHF) diet and high-intensity interval training (HIIT) program over 12 weeks on visceral adipose tissue (VAT) and cardiorespiratory fitness (CRF) level in overfat individuals.Methods: Ninety-one participants were randomly allocated to the HIIT (N = 22), VLCHF (N = 25), VLCHF+HIIT (N = 25), or control (N = 19) groups for 12 weeks. Body composition and CRF were analyzed before the experimental period and after 4, 8, and 12 weeks. Dual-energy X-ray absorptiometry (DXA) and graded exercise test (GXT) to volitional exhaustion were used for the body composition and CRF assessments, respectively.Results: There were significant between-group differences in the VAT mass and body composition outcome changes. VAT mass decreased after 12 weeks only in the VLCHF and VLCHF+HIIT groups (p &lt; 0.001, median [95% CI]: VLCHF: −142.0 [−187.0; −109.5] g; VLCHF+HIIT: −104.0 [−135.0; −71.0] g). Similarly, changes in body mass, total body fat, trunk fat mass, waist and hip circumferences were distinctly decreased in the VLCHF and VLCHF+HIIT groups, when compared to HIIT and Control groups. Total lean mass significantly decreased in the VLCHF and VLCHF+HIIT groups (−2.1 [−3.0; −1.6] kg and −2.5 [−3.6; −1.8] kg, respectively) after 12 weeks. While the HIIT program significantly increased total time to exhaustion in the GXT, peak oxygen uptake was unchanged.Conclusions: A VLCHF diet, either in isolation or in combination with HIIT, was shown to induce a significant reduction in VAT mass and body composition variables. HIIT alone did not cause such effects on body composition, but improved exercise capacity. Our findings indicate that the VLCHF diet and exercise training provoked different and isolated effects on body composition and CRF.Clinical Trial Registration: https://clinicaltrials.gov/ct2/show/NCT03934476, identifier: NCT03934476.


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