This study aimed to determine the effects of a single high-intensity interval training (HIIT) session on salivary cortisol (SC) levels, physiological responses, and performance in trained boys and men. Twenty-three boys (11.5 ± 0.8 years) and 25 men (29.7 ± 4.6 years) performed HIIT (4 consecutive Wingate Anaerobic Tests). SC in boys and men increased after HIIT from 5.55 ± 3.3 nmol/l to 15.13 ± 9.7 nmol/l (+173%) and from 7.07 ± 4.7 nmol/l to 19.19 ± 12.7 nmol/l (+171%), respectively (p < .01). Pretest SC as well as posttest changes were comparable in both groups (both p < .01). Peak blood lactate concentration was significantly lower in boys (12.6 ± 3.5 mmol/l) than in men (16.3 ± 3.1 mmol/l; p < .01). Throughout the HIIT, mean heart rates in boys were higher (p < .001) but relative peak oxygen uptake (ml·min−1·kg−1; p < .05) and performance were lower (p < .001) in boys than in men. HIIT in young athletes is associated with a higher activation of the hormonal stress axis than other types of exercise regimes as described in the literature. This study is the first to show a pronounced SC increase to HIIT in trained boys accompanied by elevated levels of blood lactate concentrations and heart rate suggesting a high cardio-respiratory, metabolic, and hormonal response to HIIT in 11-year-old boys.
Florian Engel, Sascha Härtel, Jana Strahler, Matthias Oliver Wagner, Klaus Bös and Billy Sperlich
Bonnie G. Berger, Robert W. Motl, Brian D. Butki, David T. Martin, John G. Wilkinson and David R. Owen
This study examined changes in mood and performance in response to high-intensity, short-duration overtraining and a subsequent taper. Pursuit cyclists (N = 8) at the United States Olympic Training Center completed the POMS and simulated 4-km pursuit performance tests throughout a six-week period. The six-week period included a baseline week, three weeks of overtraining that consisted primarily of high-intensity interval training, and a two-week taper. Total Mood Disturbance (TMD) scores displayed a quadratic polynomial effect across the three weeks of overtraining (p < .01), with the highest TMD scores occurring in the second week. Average TMD scores were lower during the taper than at baseline (p < .02) and lower at taper than overtraining (p < .0005). Cycling performance (pursuit time and average power output) improved during the three weeks of overtraining; additional improvements were observed during the taper. There were no significant correlations between TMD and performance. However, pursuit time, average power output, and mood disturbance scores were at optimal levels throughout the taper period. These findings suggest that high-intensity, short-duration overtraining may not result in an overtraining syndrome in 4-km pursuit cyclists.
David T. Martin, Mark B. Andersen and Ward Gates
This study examined whether the Profile of Mood States questionnaire (POMS) is a useful tool for monitoring training stress in cycling athletes. Participants (n = 11) completed the POMS weekly during six weeks of high-intensity interval cycling and a one-week taper. Cycling performance improved over the first three weeks of training, plateaued during Weeks 4 and 5, decreased slightly following Week 6, and then significantly increased during the one-week taper. Neither the high-intensity interval training nor the one-week taper significantly affected total mood or specific mood states. POMS data from two cyclists who did not show improved performance capabilities during the taper (overtraining) were not distinctly unique when compared to cyclists who did improve. Also, one cyclist, who on some days had the highest total mood disturbance, responded well to the taper and produced his best personal effort during this time period. These findings raise questions about the usefulness of POMS to distinguish, at an individual level, between periods of productive and counterproductive high-intensity training.
Keith Tolfrey, Julia Kirstey Zakrzewski-Fruer and Alice Emily Thackray
Two publications were selected because they are excellent representations of studies examining different ends of the exercise-sedentary behavior continuum in young people. The first study is an acute response study with 13 mixed-sex, mid to late adolescents presenting complete data from 4 different randomized experimental crossover conditions for analyses. Continuous glucose monitoring showed that interrupting prolonged continuous sitting with body-weight resistance exercises reduced the postprandial glucose concentration compared with a time-matched uninterrupted period of sitting. Furthermore, the effects of the breaks in sitting time were independent of the energy content of the standardized meals, but variations in the area under the glucose time curves expression were important. The second study adopted a chronic 12-week exercise training intervention design with a large sample of obese children and adolescents who were allocated randomly to high-intensity interval training (HIIT), moderate-intensity continuous training, or nutritional advice groups. HIIT was the most efficacious for improving cardiorespiratory fitness compared with the other interventions; however, cardiometabolic biomarkers and visceral/subcutaneous adipose tissue did not change meaningfully in any group over the 12 weeks. Attrition rates from both HIIT and moderate-intensity continuous training groups reduce the validity of the exercise training comparison, yet this still provides a solid platform for future research comparisons using HIIT in young people.
Tammie R. Ebert, David T. Martin, Brian Stephens and Robert T. Withers
To quantify the power-output demands of men’s road-cycling stage racing using a direct measure of power output.
Power-output data were collected from 207 races over 6 competition years on 31 Australian national male road cyclists. Subjects performed a maximal graded exercise test in the laboratory to determine maximum aerobic-power output, and bicycles were fitted with SRM power meters. Races were described as fl at, hilly, or criterium, and linear mixed modeling was used to compare the races.
Criterium was the shortest race and displayed the highest mean power output (criterium 262 ± 30 v hilly 203 ± 32 v fl at 188 ± 30 W), percentage total race time above 7.5 W/kg (crite-rium 15.5% ± 4.1% v hilly 3.8% ± 1.7% v fl at 3.5% ± 1.4%) and SD in power output (criterium 250 v hilly 165 v fl at 169 W). Approximately 67%, 80%, and 85% of total race time was spent below 5 W/kg for criterium, hilly and fl at races, respectively. About 70, 40, and 20 sprints above maximum aerobic-power output occurred during criterium, hilly, and fl at races, respectively, with most sprints being 6 to 10 s.
These data extend previous research documenting the demands of men’s road cycling. Despite the relatively low mean power output, races were characterized by multiple high-intensity surges above maximum aerobic-power output. These data can be used to develop sport-specific interval-training programs that replicate the demands of competition.
Rudolph H. Dressendorfer, Stewart R. Petersen, Shona E. Moss Lovshin and Carl L. Keen
This study examined the effects of intense endurance training on basal plasma and 24-hour urinary calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn), and copper (Cu) levels in 9 male competitive cyclists. The supervised training program followed a baseline period and included a volume phase (6 weeks, averaging 87% of maximal heart rate [HRmax]), an interval phase (18 days, 100% of HRmax), and a 10-day unloading taper. The primary training outcome measure was 20-km time-trial cycling performance. Subjects ate unrestricted diets and maintained their weight. Compared to baseline, performance improved significantly (p < .05), while mineral metabolism was not significantly different after the volume phase. However, after the interval phase, renal Ca excretion increased (p < .05) and plasma Ca fell slightly below the clinical norm. As compared to the interval phase, urinary Ca decreased (p < .05), plasma Ca increased (p < .05), and performance further improved (p < .05) after the taper. Whereas Mg, Fe, Zn, and Cu metabolism remained unchanged throughout the study, greater renal Ca excretion was associated with very high intensity interval training.
Martin Buchheit and Alireza Rabbani
The aim of the current study was to examine the relationship between performance of the Yo-Yo Intermittent Recovery Test Level 1 (Yo-YoIR1) and the 30–15 Intermittent Fitness Test (30-15IFT) and to compare the sensitivity of both tests to training. Fourteen young soccer players performed both tests before and after an 8-wk training intervention, which included 6 sessions/wk: 2 resistance training sessions, 2 high-intensity interval training sessions after technical training (4 sets of 3:30 min of generic running and small-sided games [4v4] during the first and second 4-wk periods, respectively [90–95% maximal HR], interspersed with 3 min at 60–70% maximal HR), and 2 tactical-only training sessions. There was a large correlation between 30-15IFT and Yo-YoIR1 (r = .75, 90% confidence limits [CL] 0.57;0.86). While within-test percentage changes suggested a greater sensitivity to training for the Yo-YoIR1 (+35%, 90%CL 24;45) than for the 30-15IFT (+7%; 4;10), these changes were similarly rated as almost certain (with chances for greater/similar/lower values after training of 100/0/0 for both tests) and moderate, ie, standardized difference, ES = +1.2 90%CL (0.9;1.5) for Yo-YoIR1 and ES = +1.1 (0.7;1.5) for 30-15IFT. The difference in the change between the 2 tests was clearly trivial (0/100/0, ES = –0.1, 90%CL –0.1;–0.1). Both tests might evaluate slightly different physical capacities, but their sensitivity to training is almost certainly similar. These results also highlight the importance of using standardized differences instead of percentage changes in performance to assess the actual training effect of an intervention.
Stephen F. Burns, Hnin Hnin Oo and Anh Thanh Thuy Tran
The current study examined the effect of sprint interval exercise on postexercise oxygen consumption, respiratory-exchange ratio (RER), substrate oxidation, and blood pressure in adolescents. Participants were 10 normal-weight healthy youth (7 female), age 15–18 years. After overnight fasts, each participant undertook 2 trials in a random balanced order: (a) two 30-s bouts of sprint interval exercise on a cycle ergometer and (b) rested in the laboratory for an equivalent period. Timematched measurements of oxygen consumption, RER, and blood pressure were made 90 min into recovery, and substrate oxidation were calculated over the time period. Total postexercise oxygen uptake was significantly higher in the exercise than control trial over the 90 min (mean [SD]: control 20.0 [6.0] L, exercise 24.8 [9.8] L; p = .030). After exercise, RER was elevated above control but then fell rapidly and was lower than control 30–60 min postexercise, and fat oxidation was significantly higher in the exercise than control trial 45–60 min postexercise. However, total fat oxidation did not differ between trials (control 4.5 [2.5] g, exercise 5.4 [2.7] g; p = .247). Post hoc tests revealed that systolic blood pressure was significantly lower than in control at 90 min postexercise (control 104  mm Hg, exercise 99  mm Hg; p < .05). These data indicate that acute sprint interval exercise leads to short-term increases in oxygen uptake and reduced blood pressure in youth. The authors suggest that health outcomes in response to sprint interval training be examined in children.
24 24 6 6 Interval Training Intensity Affects Energy Intake Compensation in Obese Men Shaea A. Alkahtani * Nuala M. Byrne * Andrew P. Hills * Neil A. King * 12 2014 24 24 6 6 595 595 604 604 10.1123/ijsnem.2013-0032 Combined Glucose Ingestion and Mouth Rinsing Improves Sprint Cycling
.2019-0118 jsep.2019-0118 Psychological Responses to High-Intensity Interval Training: A Comparison of Graded Walking and Ungraded Running at Equivalent Metabolic Loads Abby R. Fleming * Nic Martinez * Larry H. Collins * Candi D. Ashley * Maureen Chiodini * Brian J. Waddell * Marcus W