Background/Aim: Reduced-exertion high-intensity interval training (REHIT) is a genuinely

Purpose: Recent studies have demonstrated that modifying the 'classic' 6x30-s 'all-out' sprint interval training (SIT) protocol by incorporating either shorter sprints (6x10-s or 15-s sprints) or fewer sprints (e.g. 2x20-s sprints; reduced-exertion high-intensity interval training (REHIT)) does not attenuate the training-induced improvements in maximal aerobic capacity (VȮ2max). The aim of the present study was to determine whether reducing the sprint duration in the REHIT protocol from 20 s to 10 s per sprint influences acute affective responses and the change in VȮ2max following training. ) were randomised to a group performing a 'standard' REHIT protocol involving 2x20-s sprints or a group who performed 2x10-s sprints. VȮ2max was determined before and after 6 weeks of 3 weekly training sessions. Acute affective responses and perceived exertion were assessed during training. Methods Results: Greater increases in

for assistance in training supervision for study 3. We would also like to extend a special thank you to our family and friends for their support during our academic endeavours.

Myokines may play a role in the health benefits of regular physical activity. Secreted protein acidic rich in cysteine (SPARC) is a pleiotropic myokine that has been shown to be released into the bloodstream by skeletal muscle in response to aerobic exercise. As there is evidence suggesting that SPARC release may be linked to glycogen breakdown and activation of 5' adenosine monophosphate-activated protein kinase, we hypothesised that brief supramaximal exercise may also be associated with increased serum SPARC levels. In the present study, 10 participants (3 women; mean ± SD age: 21 ± 3 y, body mass index (BMI): 22 ± 3 kg m, and V˙O: 39 ± 6 mL kg min) performed an acute bout of supramaximal cycle exercise (20-s Wingate sprint against 7.5% of body mass, with a 1-min warm-up and a 3-min cool-down consisting of unloaded cycling). Serum SPARC levels were determined pre-exercise as well as 0, 15, and 60 min post-exercise and corrected for plasma volume change. To determine whether regular exercise affected the acute SPARC response, participants repeated the acute exercise protocol three times per week for four weeks, and serum SPARC response to supramaximal exercise was reassessed after this period. Acute supramaximal exercise significantly decreased plasma volume (-10%; p < .001), but was not associated with a significant change in serum SPARC levels at either the pre-training or post-training testing sessions. In conclusion, in contrast to aerobic exercise, a single brief supramaximal cycle sprint is not associated with an increase in serum SPARC levels, suggesting that SPARC release is not related to skeletal muscle glycogen breakdown.

PurposeSprint interval training (SIT) provides a potent stimulus for improving maximal aerobic capacity (), which is among the strongest markers for future cardiovascular health and premature mortality. Cycling-based SIT protocols involving six or more ‘all-out’ 30-s Wingate sprints per training session improve , but we have recently demonstrated that similar improvements in can be achieved with as few as two 20-s sprints. This suggests that the volume of sprint exercise has limited influence on subsequent training adaptations. Therefore, the aim of the present study was to examine whether a single 20-s cycle sprint per training session can provide a sufficient stimulus for improving .MethodsThirty sedentary or recreationally active participants (10 men/20 women; mean ± SD age: 24 ± 6 years, BMI: 22.6 ± 4.0 kg m−2, : 33 ± 7 mL kg−1 min−1) were randomised to a training group or a no-intervention control group. Training involved three exercise sessions per week for 4 weeks, consisting of a single 20-s Wingate sprint (no warm-up or cool-down). was determined prior to training and 3 days following the final training session.ResultsMean did not significantly change in the training group (2.15 ± 0.62 vs. 2.22 ± 0.64 L min−1) or the control group (2.07 ± 0.69 vs. 2.08 ± 0.68 L min−1; effect of time: P = 0.17; group × time interaction effect: P = 0.26).ConclusionAlthough we have previously demonstrated that regularly performing two repeated 20-s ‘all-out’ cycle sprints provides a sufficient training stimulus for a robust increase in , our present study suggests that this is not the case when training sessions are limited to a single sprint.