Weeks Of Sprint Interval Training Research Articles

Interval training causes the same exercise enjoyment as moderate-intensity training to improve cardiorespiratory fitness and body composition in young Chinese women with elevated BMI

ABSTRACT This study examined the effects of 12 weeks of sprint interval training (SIT), high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on cardiorespiratory fitness (peak oxygen uptake, VO2peak), body composition and physical activity enjoyment in overweight young women. Sixty-six participants (age 21.2 ± 1.4 years, body mass index (BMI) 26.0 ± 3.0 kg·m−2, body fat percentage 39.0 ± 2.8%) were randomly assigned to non-exercise control (CON), thrice-weekly SIT (80 × 6 s “all-out” cycling interspersed with 9 s rest), and HIIT (4 min cycling at 90% VO2peak followed with 3 min recovery for ~ 60 min) or MICT (~ 65 min continuous cycling at 60% VO2peak) with equivalent mechanical work (200/300 KJ). Compared to the CON group, all three training groups had significant and similar improvements in VO2peak (~ +20%, d = 2.5–3.4), fat mass (~ −10%, d = 1.3–2.1) and body fat percentage (~ −5%, d = 1.0–1.1) after a 12-week intervention. Similar high levels of enjoyment were observed among groups for most (~70%) of the training sessions. The findings suggest that the three training regimes are equally enjoyable and could result in similar improvements in cardiorespiratory fitness and body composition in overweight/obese young women, but SIT is a more time-efficient strategy.

The Effects of Anaerobic Swim Ergometer Training on Sprint Performance in Adolescent Swimmers.

The purpose of this study was to compare 4 weeks of pool-based sprint interval training with a similar ergometer training intervention on a maximal anaerobic lactate test (MANLT), 50-m (competition) freestyle performance, and 6- and 30-second maximal swimming ergometer performances. A total of 14 competitive adolescent swimmers (male, n = 8; female, n = 6) participated in this study. Swimmers were categorized into 2 sex-matched groups: swimming ergometer (ERG; n = 7) and pool-sprint training (n = 7) groups. Each athlete performed 4 preintervention and postintervention assessments consisting of a MANLT, a 50-m freestyle race, and 6- and 30-second maximal swim ERG performances. Both groups demonstrated a significant effect (P < .05) of time for all assessments. Group differences were observed after 4 weeks of sprint interval training as follows: (1) The ERG group had a significantly faster speed in the fourth 50-m MANLT sprint (ERG 1.58 [0.05] vs pool-sprint training 1.48 [0.07]m/s, P < .01) and (2) The ERG group demonstrated enhanced Δblood lactate post-MANLT (ERG 2.4 [1.2] vs pool-sprint training 2.7 [0.9]mmol/L, P < .05). A significant correlation was found between the 30-second maximal ERG test and 50-m freestyle swimming velocity (r = .74, P < .01, effect size = 0.52). The results demonstrate significant physiological improvements to anaerobic sprint ability after 4 weeks of sprint interval training in both swim ERG and pool-based interventions. Thus, sprint ability may be improved through multiple modalities (pool and dry land) to elicit a positive training response.

Comparison of physiological and clinical markers for chronic sprint-interval training exercise performed either in the fasted or fed states among healthy adults.

ObjectiveSprint-interval training (SIT) and intermittent fasting are effective independent methods in achieving clinical health outcomes. However, the impact of both modalities when performed concurrently is unclear. The aim of this study was to compare the effects of 6 weeks of SIT performed in the fasted versus fed state on physiological and clinical health markers in healthy adults. Methods. Thirty recreationally-active participants were equally randomised into either the fasted (FAS; 4 males, 11 females) or the fed (FED; 6 males, 9 females) group. For all exercise sessions, FAS participants had to fast ≥10 h prior to exercising while FED participants had to consume food within 3 h to exercise. All participants underwent three sessions of SIT per week for 6 weeks. Each session consists of repeated bouts of 30-s Wingate Anaerobic cycle exercise. Pre- and post-training peak oxygen uptake (VO2peak), isokinetic leg strength, insulin sensitivity, blood pressure and serum lipid levels were assessed. Results. There were no differences in baseline physiological and clinical measures between both groups (all p > 0.05). VO2peak improved by 6.0 ± 8.8% in the FAS group and 5.3 ± 10.6% in the FED group (both p < 0.05), however the difference in improvement between groups was not statistically significant (p > 0.05). A similar pattern of results was seen for knee flexion maximum voluntary contraction at 300°·s−1. SIT training in either fasted or fed state had no impact on insulin sensitivity (both p > 0.05). There was significant reduction in diastolic blood pressure (8.2 ± 4.2%) and mean arterial pressure (7.0 ± 3.2%) in the FAS group (both p < 0.05) but not FED group (both p > 0.05). Conclusion. VO2peak and leg strength improved with SIT regardless of whether participants trained in the fasted or fed state. Chronic SIT in the fasted state may potentially reduce blood pressure to a greater extent than the same chronic SIT in the fed state.

Response to Three Weeks of Sprint Interval Training Cannot Be Explained by the Exertional Level.

Background and Objectives: The all-out mode of sprint interval training (SIT) has been shown to be an efficient method for improving sports performance, exercise capacity, and aerobic fitness. Although the benefits of SIT are well described, the mechanisms underlying the different degrees of response remain largely unexplored. We aimed to assess the effects of exertion on the responsiveness to SIT. Materials and Methods: The participants were 28 young untrained men (mean ± SD age 25.7 ± 6.03 years) who exhibited either a large or small increase in Wingate test average power in response to nine SIT sessions performed over three weeks. Each training session comprised four–six bouts of 30 s all-out cycling interspaced with 4 min of rest. Individual responses were assessed using heart rate (HR) during exercise for all nine sessions, as well as blood lactate concentration up to 1 h, and the decrement in maximal voluntary knee extension torque (MVC) up to 24 h after the first and last training sessions. Peak oxygen uptake (VO2peak) and maximum HR were measured before and after training during an incremental cycling test to exhaustion. Results: Although all participants showed benefits of SIT such as increased VO2peak, the increase in anaerobic cycling power varied between participants. We identified 17 high responders and nine low responders, whose average power outputs were 0.80 ± 0.22 and 0.22 ± 0.19 W/kg, respectively. The HR achieved during any of the training sessions did not differ between high and low responders. The lactate kinetics did not differ between groups before and after the intervention. Training resulted in a more rapid recovery of MVC without any discernible differences between the high and low responders. Conclusion: The differences in the responses to SIT are not dependent on the exertion level during training.

A Better Approach To Improve Cardiovascular Function In Middle-aged, Inactive Human

PURPOSE: Investigate whether different aquatic aerobic exercise intensity modalities yield differential effects on vascular and endothelial function in middle-aged, inactive human METHODS: A randomized, controlled trial of middle-aged with inactive recipients 6 weeks of sprint interval training (SIT) or 6 weeks of moderate-intensity continued training (MICT). Outcomes included arterial stiffness, endothelial function, lipid metabolism, body composition and aerobic capacity. RESULTS: Twenty-six middle-aged with inactive human (mean age 41 years, 73% male) completed the study. The decrease (P<0.05) of [email protected] (augmentation index at HR of 75 beat/min) in SIT group was greater than MICT group. On the contrary, subendocardial viability ratio (SEVR) was elevated in the MICT (P<0.01) groups but not after SIT. Brachial artery BP decreased (P<0.01) by -8.1±1.5 mmHg after MICT exercise with no change in SIT. Both groups could significantly reduce fasting blood glucose (P<0.001), but only the decrease of total cholesterol was found in SIT (P<0.01). Brachial artery Flow-mediated vasodilation (FMD) was improved in both group, MICT only showed marginal significance(P=0.07)compared with SIT (P<0.05). SIT's relative VO2max and O2 pulse increased (P<0.05) by 8.4% and 8.6%, respectively, with no change in MICT. Both groups of interventions could reduce BMI (P<0.05), but SIT was mainly by increasing lean body mass (P<0.01) and decreasing fat mass (P<0.001), while the lean body mass of MICT did not change. CONCLUSIONS: The results of the present study demonstrate that short-term low-volume aquatic SIT is a time-efficient strategy to induce changes in arterial vascular stiffness, endothelial function, lipid metabolism and body composition during exercise that are comparable to changes induced by water-based traditional high-volume MICT.

Oral Contraceptive Use Influences On-Kinetic Adaptations to Sprint Interval Training in Recreationally-Active Women.

IntroductionOral contraceptive (OC) use influences peak exercise responses to training, however, the influence of OC on central and peripheral adaptations to exercise training are unknown. This study investigated the influence of OC use on changes in time-to-fatigue, pulmonary oxygen uptake, cardiac output, and heart rate on-kinetics, as well as tissue saturation index to 4 weeks of sprint interval training in recreationally active women.MethodsWomen taking an oral contraceptive (OC; n = 25) or experiencing natural menstrual cycles (MC; n = 22) completed an incremental exercise test to volitional exhaustion followed by a square-wave step-transition protocol to moderate (90% of power output at ventilatory threshold) and high intensity (Δ50% of power output at ventilatory threshold) exercise on two separate occasions. Time-to-fatigue, pulmonary oxygen uptake on-kinetics, cardiac output, and heart rate on-kinetics, and tissue saturation index responses were assessed prior to, and following 12 sessions of sprint interval training (10 min × 1 min efforts at 100–120% PPO in a 1:2 work:rest ratio) completed over 4 weeks.ResultsTime-to-fatigue increased in both groups following training (p < 0.001), with no difference between groups. All cardiovascular on-kinetic parameters improved to the same extent following training in both groups. Greater improvements in pulmonary oxygen up-take kinetics were seen at both intensities in the MC group (p < 0.05 from pre-training) but were blunted in the OC group (p > 0.05 from pre-training). In contrast, changes in tissue saturation index were greater in the OC group at both intensities (p < 0.05); with the MC group showing no changes at either intensity.DiscussionOral contraceptive use may reduce central adaptations to sprint interval training in women without influencing improvements in exercise performance - potentially due to greater peripheral adaptation. This may be due to the influence of exogenous oestradiol and progestogen on cardiovascular function and skeletal muscle blood flow. Further investigation into female-specific influences on training adaptation and exercise performance is warranted.

Sprint interval training in young adult males with & without elevated worry

Using a pre-post design, we investigated state anxiety and worry responses to a single Wingate, three weeks of sprint interval training (SIT), and, change in response to a single Wingate. Differences between males with and without elevated worry were explored. Thirty-eight young adult males, 18 with elevated worry (Penn State Worry Questionnaire [PSWQ] ≥45), completed a single 30s Wingate at 7.5% body mass before and after three weeks of SIT (nine sessions of 4–6 sprints). The state subscale of the State-Trait Anxiety Inventory assessed state anxiety; the PSWQ measured worry and worry engagement. A single Wingate increased state anxiety (d = -0.37, [-0.82, 0.09]) and decreased worry engagement (d = 0.16, [-0.29, 0.61]). SIT resulted in non-significant reductions in state anxiety (d = 0.20, [-0.25, 0.65]) and worry (d = 0.09, [-0.36, 0.54]). SIT non-significantly attenuated state anxiety response to a single Wingate (d = 0.23, [-0.22, 0.68]), approximating a 2.5-fold reduction from pre- (d = -0.37, [-0.82, 0.09]) to post-SIT (d = -0.16, [-0.61, 0.29]). Improvements in worry (d = 0.61, [-0.04, 1.26]) and worry engagement (d = 0.60, [-0.05, 1.25]) were moderately larger among males with elevated worry. Findings indicated that a single Wingate may acutely perturb state anxiety and improve worry. Three weeks of SIT may improve anxiety and worry and response to a single Wingate. Responses were moderately larger among males with elevated worry.

Six Sessions of Sprint-Interval Training Did Not Improve Endurance and Neuromuscular Performance in Untrained Men.

Previous research demonstrated that six sessions of cycling sprint-interval training (SIT) within a duration of only 2 weeks can increase endurance performance considerably. Primarily muscular mechanisms have been under investigation explaining such performance improvements. However, it has been shown in other exercise tasks that training-induced changes also occur at the level of the central nervous system. Therefore, we hypothesized to observe an enhanced neuromuscular performance in conjunction with an increase in endurance performance after 2 weeks of SIT. Therefore, we randomly assigned 19 healthy men (26 ± 5 years) to a control (n = 10) or a training group (n = 9), the latter performing a replication of the SIT protocol from Burgomaster et al. Before and after the training intervention, both groups performed a cycling endurance test until exhaustion. Neuromuscular function of the right vastus lateralis muscle was assessed before and after each endurance task by the means of maximal voluntary isometric contractions (MVCs). The variables of interest being MVC, voluntary activation was measured by peripheral nerve stimulations (VAPNS), by transcranial magnetic stimulation (VATMS), as well as potentiated resting twitches (Qtw,pot). We did not find any significant differences between the groups in the control variable time to exhaustion in the endurance task. In addition, we did not observe any time × group interaction effect in any of the neuromuscular parameters. However, we found a significant large-sized time effect in all neuromuscular variables (MVC, = 0.181; VATMS, = 0.250; VAPNS, = 0.250; Qtw,pot, = 0.304) as well as time to exhaustion = 0.601). In contrast to other studies, we could not show that a short-term SIT is able to increase endurance performance. An unchanged endurance performance after training most likely explains the lack of differences in neuromuscular variables between groups. These findings demonstrate that replication studies are needed to verify results no matter how strong they seem to be. Differences over time for the variables of neuromuscular fatigue irrespective of group (MVC, + 9.3%; VATMS, + 0.2%; VAPNS, + 6.3%; Qtw,pot, + 6.3%) demonstrate test-retest effects that should be taken into consideration in future training studies and emphasize the inevitable necessity for controlled experiments.

Sprint interval training versus moderate-intensity continuous training during inpatient rehabilitation after spinal cord injury: a randomized trial.

Randomized trial. To evaluate the effectiveness of a 5-week sprint interval training (SIT) protocol on an arm-crank ergometer in individuals with sub-acute spinal cord injury (SCI). Inpatient rehabilitation. Individuals with SCI (N = 20; 9 tetraplegia/11 paraplegia; time since injury, 14-182 days; age, 46 ± 16 years; 15 M/5 F) were randomized to SIT or moderate-intensity continuous training (MICT). SIT consisted of 3 × 20 s. 'all-out' cycle sprints (≥100% peak power output) interspersed with 2 min of active recovery (10% peak power output; total time commitment, 10 mins). MICT involved 20 min of cycling (45% peak power output; total time commitment, 25 mins). Both training interventions were delivered 3 times/week for 5 weeks. Heart rate and Borg's Rating of Perceived Exertion (RPE; 6-20) were monitored throughout training sessions. Maximal and sub-maximal power outputs were assessed on an arm-crank ergometer. Exercise enjoyment, exercise self-efficacy, and pain were assessed at the end of the intervention. During training sessions, heart rate (135 bpm vs. 119 bpm; p = 0.05), peripheral RPE (16 vs. 12; p = 0.000), and central RPE (15 vs. 11; p = 0.004) responses were higher in the SIT group, yet total work performed was greater in MICT. Peak power output increased significantly with training (36%), with no difference between groups (39% vs. 33%; p = 0.524). Similarly, improvements in sub-maximal power output were not different across groups. There were no between-group differences in exercise enjoyment (p = 0.385), exercise self-efficacy (p = 0.930), or pain (p = 0780). Five weeks of SIT improved physical capacity to the same extent as MICT in individuals with sub-acute SCI, despite a significantly lower time commitment with SIT.

CrossTalk proposal: Exercise training intensity is more important than volume to promote increases in human skeletal muscle mitochondrial content.

CrossTalk proposal: Exercise training intensity is more important than volume to promote increases in human skeletal muscle mitochondrial content.

Three weeks of sprint interval training improved high-intensity cycling performance and limited ryanodine receptor modifications in recreationally active human subjects.

Mechanisms underlying the efficacy of sprint interval training (SIT) remain to be understood. We previously reported that an acute bout of SIT disrupts the integrity of the sarcoplasmic reticulum (SR) Ca2+ release channel, the ryanodine receptor 1 (RyR1), in recreationally active human subjects. We here hypothesize that in addition to improving the exercise performance of recreationally active humans, a period of repeated SIT sessions would make the RyR1 protein less vulnerable and accelerate recovery of contractile function after a SIT session. Eight recreationally active males participated in a 3-week SIT program consisting of nine sessions of four-six 30-s all-out cycling bouts with 4min of rest between bouts. Total work performed during a SIT session and maximal power (Wmax) reached during an incremental cycling test were both increased by ~ 7.5% at the end of the training period (P < 0.05). Western blots performed on vastus lateralis muscle biopsies taken before, 1h, 24h and 72h after SIT sessions in the untrained and trained state showed some protection against SIT-induced reduction of full-length RyR1 protein expression in the trained state. SIT-induced knee extensor force deficits were similar in the untrained and trained states, with a major reduction in voluntary and electrically evoked forces immediately and 1h after SIT (P < 0.05), and recovery after 24h. Three weeks of SIT improves exercise performance and provides some protection against RyR1 modification, whereas it does not accelerate recovery of contractile function.

Examining Work-to-Rest Ratios to Optimize Upper Body Sprint Interval Training

PURPOSE: The primary purpose of this study was evaluate the effectiveness of upper body sprint interval training (SIT) protocols with varying work-to-rest ratios on both aerobic and anaerobic performance. The secondary purpose was to investigate the changes in metabolic and neuromuscular fatigue thresholds from two weeks of SIT in recreationally active men. METHODS: Forty-two recreationally trained men were randomized into one of three training groups [10s work bouts with two minutes of rest (10:2) or four minutes of rest (10:4), or 30s work bouts with four minutes of rest (30:4)] or a control group (CON). Participants underwent six training sessions over two weeks with four to six ‘all-out’ sprints. During pre- and post-intervention visits, participants underwent a graded exercise test to determine maximal oxygen consumption (V̇ O2peak) and peak power output (PPO), four constant-work rate trials to determine critical power (CP), anaerobic working capacity (W’), and electromyographic fatigue threshold (EMGFT), and an upper body Wingate test to determine peak power (PP), mean power (MP), and total work (TW). An analysis of covariance was performed on all testing measurements collected at post with the associated pre-values used as covariates. RESULTS: There were significant between group differences in post-test absolute V̇ O2peak, with an adjusted pre-test mean of 2.44L·min-1, and PPO, with an adjusted pre-test mean of 130.9W. Absolute V̇ O2peak was greater in 30:4 (2.36±0.26L·min-1, p = .007) and 10:2 (2.53±0.38L·min-1, p = .036) than CON (2.17±0.34L·min-1), and PPO was greater in 30:4 than CON (136±14 vs. 127±22W, p = .007, respectively). No differences were observed between groups in CP (p = .530), W’ (p = .900), EMGFT (p = .692), PP (p = .692), MP (p = .290), or TW (p = .291). CONCLUSION: SIT protocols with larger work-to-rest ratios appears to have enhanced V̇ O2peak in the upper body over a short-term two-week intervention.

State Anxiety and Worry Responses to a Single Sprint Before and After Sprint Interval Training

There has been continued interest in the anxiolytic effects of diverse and non-traditional exercise modes. However, the acute and chronic effects of sprint interval training (SIT) on anxiety and worry are not well known, and the degree to which chronic SIT changes the acute response to a single sprint is untested. PURPOSE: This study quantified state anxiety and worry responses to a single sprint (Wingate), state anxiety and worry responses to three weeks of SIT, and, the extent to which chronic SIT changed acute responses to a single sprint. METHODS: Eighteen healthy young adult males (25.2±3.6 y) completed a single 30s Wingate at 7.5% body mass before and after a 3-wk SIT intervention comprised of nine sessions of 4-6 sprints. Acute and chronic effects of SIT on state anxiety, worry, and worry engagement were assessed with the State subscale of the State-Trait Anxiety Inventory and the Penn State Worry Questionnaire, respectively. Paired t-tests quantified pre-training acute responses and training responses (i.e., baseline to post-SIT); magnitude of change was quantified with standardized mean difference (d). RM-ANOVA examined differences between pre-training and post-training acute responses. The magnitude of change in acute responses was quantified with Hedges’ d effect sizes. RESULTS: At pre-training, state anxiety was significantly increased (t17=-2.34, p≤0.032) and worry engagement was significantly decreased (t17=3.14, p≤0.006) following a single sprint. Small-to-moderate magnitude reductions were found for worry engagement (d=0.37) and worry (d=0.18), and a small-to-moderate magnitude increase was found for state anxiety (d=-0.36). No statistically significant changes were found for state anxiety, worry, or worry engagement following SIT (all p>0.23); however, small magnitude reductions were found for state anxiety (d=0.11), worry (d=0.26), and worry engagement (d=0.21). Following SIT, a statistically non-significant small magnitude attenuation (d=0.14) of state anxiety response to a single sprint was found. CONCLUSION: Findings provide proof of principle that even a single high-intensity sprint can acutely perturb state anxiety and improve worry. Short-term SIT may elicit improved resting levels of anxiety and worry and response to a single high-intensity sprint in healthy young men.

Cardiovascular response of postmenopausal women to 8weeks of sprint interval training.

Menopause is accompanied by decreased aerobic fitness and increased risk of cardiovascular disease. Sprint interval training (SIT) is a time-efficient intervention for improving cardiovascular function and aerobic fitness of young adults. To determine the effect of an 8-week SIT program on the cardiovascular function and aerobic fitness of overweight postmenopausal women. Thirty overweight postmenopausal women were randomized into exercise (n = 15) or control (n = 15) groups. The intervention group completed three SIT sessions a week for 8weeks. Each session consisted of 20min of 8-s sprints and 12s of light pedalling. Participants also completed 8min of light aerobic cycle exercise, before and after the SIT intervention. Cardiovascular function including heart rate, stroke volume (SV), and diastolic filling time (DFT) was assessed before and after the intervention and during 8min of light aerobic exercise. Estimated maximal oxygen uptake ([Formula: see text]) was also assessed. Resting SV was increased (p = 0.001) from pre- (77.5 ± 17.0mL) to post-SIT (81.3 ± 17.0mL), whereas SV during 8min of light aerobic exercise was increased (p = 0.000), from pre- (97.8 ± 1.6mL) to post-test (103.5 ± 17.8mL). Resting DFT was increased, (p = 0.010), at pre- (333.4 ± 94.4mL) to post-SIT (357.4 ± 88.2mL), whereas DFT during 8min of aerobic exercise was increased, (p = 0.000), from pre- (480.1 ± 99.5mL) to posttest (527.2 ± 123.0mL). Predicted [Formula: see text] was increased, (p = 0.016), from pre- (19.5 ± 5.87mLkg-1min-1) to post-SIT (21.4 ± 7.02mLkg-1min-1). SIT improved cardiovascular function and aerobic fitness of overweight postmenopausal women after 8weeks of exercise.

Effects of six-week sprint interval or endurance training on calculated power in maximal lactate steady state.

The purpose of the study was to evaluate and compare the influence of sprint interval training (SIT) and endurance training (ET) on calculated power in maximal lactate steady state (PMLSS) (influenced by the maximal lactate production rate (⩒Lamax) and maximal oxygen uptake (⩒O2max)). Thirty participants were randomly assigned to the a) SIT, b) ET, or c) control group (n = 10 each). Each session consisted of four to six repetitions of 30 s all-out effort Wingate anaerobic tests (SIT) or 60 min cycling at 1.5 to 2.5 mmol∙L-1 blood lactate (analysed every 10 min). Both groups performed training on three days per week, over a period of six weeks. To measure ⩒Lamax and ⩒O2max, and to calculate PMLSS, sprint and ramp tests were performed at baseline and after two, four and six weeks of intervention. While SIT resulted in a significant reduction of ⩒Lamax (-0.08 ± 0.05 mmol∙L-1∙s-1, p=0.003) after two weeks and remained subsequently stable, ⩒O2max (+2.6 ± 2.4 ml∙min-1∙kg-1, p = 0.044) and PMLSS (+25 ± 14 W, p=0.002) increased, but not before six weeks of SIT. After two weeks of ET, ⩒Lamax remained unchanged, but ⩒O2max increased by increased by +2.9 ± 2.4 ml∙min-1∙kg-1, p=0.03, and after six weeks by 5.6 ± 3.5 ml∙min-1∙kg-1. The increase of PMLSS was significant after four weeks of ET (+16 ± 14 W, p=0.036) and increased to +32 ± 17 W after six weeks. Comparison of SIT and ET revealed no significant differences for ⩒Lamax, ⩒O2max or PMLSS after six weeks. The control group remained stable in all parameters. In both exercising groups there was a significant improvement of the calculated PMLSS due to different influences of ⩒Lamax and ⩒O2max.

The Effects of Acute and Chronic Sprint-Interval Training on Cytokine Responses Are Independent of Prior Caffeine Intake.

We examined the effect of acute and chronic sprint interval training (SIT), with or without prior caffeine intake, on levels of exercise-induced inflammatory plasma cytokines [interleukin (IL)-6, IL-10, tumor necrosis factor (TNF)-α]. Twenty physically-active men ingested either a placebo (n = 10) or caffeine (n = 10) 1 h before each SIT session(13-s × 30-s sprint/15 s of rest) during six training sessions (2 weeks). The early (before, immediately after, and 45 min after the exercise) and late (24 and 48 h after the exercise) cytokine and creatine kinase (CK) responses were analyzed for the first and last training sessions. Plasma IL-6 and IL-10 peaked 45 min after the exercise, and then returned to basal values within 24 h (p < 0.05) in both groups on both occasions (p > 0.05). On both occasions, and for both groups, plasma TNF-α increased from rest to immediately after the exercise and then decreased at 45 min before reaching values at or below basal levels 48 h after the exercise (p < 0.05). Serum CK increased from rest to 24 and 48 h post-exercise in the first training session (p < 0.05), but did not alter in the last training session for the PLA group (p > 0.05). Serum CK was unchanged in both the first and last training sessions for the CAF group (p > 0.05). Two weeks of SIT induced a late decrease in the IL-6/IL-10 ratio (p < 0.05) regardless of caffeine intake, suggesting an improved overall inflammatory status after training. In conclusion, a single session of SIT induces muscle damage that seems to be mitigated by caffeine intake. Two weeks of SIT improves the late SIT-induced muscle damage and inflammatory status, which seems to be independent of caffeine intake.

Improvements in Attention and Cardiac Autonomic Modulation After a 2-Weeks Sprint Interval Training Program: A Fidelity Approach.

This study aimed to: (1) investigate the influence of a 2-weeks sprint interval training (SIT) program on aerobic capacity, cardiac autonomic control, and components of attention in young healthy university students; and (2) to ascertain whether training fidelity would influence these adaptations. One hundred and nine participants were divided into an experimental (EG) and control (CG) groups. The EG performed a SIT program that consisted of 6 sessions of 4 × 30 s “all-out” efforts on a cycle ergometer, interspersed with active rests of 4 min. The criterion for fidelity was achieving >90% of estimated maximum heart rate (HR) during sprint bouts. After analyses, the EG was divided into HIGH (n = 26) and LOW (n = 46) fidelity groups. Components of attention were assessed using the Attention Network Test (ANT). Aerobic capacity (VO2max) was estimated while the sum of skinfolds was determined. Autonomic control of HR was assessed by means of HR variability (HRV) and HR complexity at rest and during ANT. Both HIGH and LOW significantly increased aerobic capacity, vagal modulation before and during ANT, and executive control, and decreased body fatness after SIT (p < 0.05). However, only participants from HIGH showed an increase in HR complexity and accuracy in ANT when compared to LOW (p < 0.05). Two weeks of SIT improved executive control, body fatness, aerobic fitness, and autonomic control in university students with better results reported in those individuals who exhibited high fidelity.

Energy compensation after sprint- and high-intensity interval training.

BackgroundMany individuals lose less weight than expected in response to exercise interventions when considering the increased energy expenditure of exercise (ExEE). This is due to energy compensation in response to ExEE, which may include increases in energy intake (EI) and decreases in non-exercise physical activity (NEPA). We examined the degree of energy compensation in healthy young men and women in response to interval training.MethodsData were examined from a prior study in which 24 participants (mean age, BMI, & VO2max = 28 yrs, 27.7 kg•m-2, and 32 mL∙kg-1∙min-1) completed either 4 weeks of sprint-interval training or high-intensity interval training. Energy compensation was calculated from changes in body composition (air displacement plethysmography) and exercise energy expenditure was calculated from mean heart rate based on the heart rate-VO2 relationship. Differences between high (≥ 100%) and low (< 100%) levels of energy compensation were assessed. Linear regressions were utilized to determine associations between energy compensation and ΔVO2max, ΔEI, ΔNEPA, and Δresting metabolic rate.ResultsVery large individual differences in energy compensation were noted. In comparison to individuals with low levels of compensation, individuals with high levels of energy compensation gained fat mass, lost fat-free mass, and had lower change scores for VO2max and NEPA. Linear regression results indicated that lower levels of energy compensation were associated with increases in ΔVO2max (p < 0.001) and ΔNEPA (p < 0.001).ConclusionsConsiderable variation exists in response to short-term, low dose interval training. In agreement with prior work, increases in ΔVO2max and ΔNEPA were associated with lower energy compensation. Future studies should focus on identifying if a dose-response relationship for energy compensation exists in response to interval training, and what underlying mechanisms and participant traits contribute to the large variation between individuals.

Cold-water immersion following sprint interval training does not alter endurance signaling pathways or training adaptations in human skeletal muscle.

We investigated the underlying molecular mechanisms by which postexercise cold-water immersion (CWI) may alter key markers of mitochondrial biogenesis following both a single session and 6 wk of sprint interval training (SIT). Nineteen men performed a single SIT session, followed by one of two 15-min recovery conditions: cold-water immersion (10°C) or a passive room temperature control (23°C). Sixteen of these participants also completed 6 wk of SIT, each session followed immediately by their designated recovery condition. Four muscle biopsies were obtained in total, three during the single SIT session (preexercise, postrecovery, and 3 h postrecovery) and one 48 h after the last SIT session. After a single SIT session, phosphorylated (p-)AMPK, p-p38 MAPK, p-p53, and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) mRNA were all increased (P < 0.05). Postexercise CWI had no effect on these responses. Consistent with the lack of a response after a single session, regular postexercise CWI had no effect on PGC-1α or p53 protein content. Six weeks of SIT increased peak aerobic power, maximal oxygen consumption, maximal uncoupled respiration (complexes I and II), and 2-km time trial performance (P < 0.05). However, regular CWI had no effect on changes in these markers, consistent with the lack of response in the markers of mitochondrial biogenesis. Although these observations suggest that CWI is not detrimental to endurance adaptations following 6 wk of SIT, they question whether postexercise CWI is an effective strategy to promote mitochondrial biogenesis and improvements in endurance performance.

Effect Of Sprint Interval &amp; Eccentric Training On Gene Expression Levels Of Caspase3 &amp; Bax/bcl-2 In Rat Skeletal Muscle

PURPOSE: Apoptosis is a process of programmed cell death that occurs in different stress factors in the body. One of these stresses is exercise, exercise is a strong physiological stimulus which can influence a number of intracellular and extracellular signaling pathways. Till now, few researches shows the effect of sprint interval training and eccentric training on caspase3, bcl2 and bax gene expression changes. This study is exploring the effect of nine weeks of sprint interval training and eccentric training on caspase3, bcl2 and bax expression in soleus and SVL muscles METHODS: twenty four male Sprague Dawley rats purchased from Razi Institute were divided into three groups: control (n=8), sprint interval training (n=8) and eccentric training (n=8). Sprint interval training was included of one minute sprinting on animal treadmill with 2-4 minutes rest, 6-10 sets per session on 5-6 days a week, and eccentric downhill running was included running on -16° slope with 16 m/min for 90 minutes which in both the intensity of the trainings during the nine weeks gradually increased. The evaluation of gene expression was done by Real time PCR method RESULTS: Considering the low number of samples (n=8) and the normality of data rejected by Shapiro-Wilk test, Mann Whitney teat for differential between training and control groups were used. Also, caspase3 expression increased in all groups. All of these differences were not significant except for soleus muscle of eccentric training group. Also Bax/bcl-2 ratio increased in all groups and All of these differences were not significant. CONCLUSIONS: we conclude that nine weeks of Sprint interval training could lead to a small increase in caspase3 expression, Bax/bcl-2 ratio as the influential factor of apoptosis in all groups, except a large increase in caspase3 expression and ultimately strong apoptosis for soleus muscle in eccentric training group. Furthermore, it should be mentioned that the type of training and muscle could influenced the amount of gene expression levels of caspase3, bax/bcl2.