Effects of short sprint interval training on aerobic and anaerobic indices: A systematic review and meta-analysis.

The effects of short sprint interval training (sSIT) with efforts of ≤10 s on maximal oxygen consumption (V̇O2 max), aerobic and anaerobic performances remain unknown. To verify the effectiveness of sSIT in physically active adults and athletes, a systematic literature search was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The databases PubMed/MEDLINE, ISI Web of Science, and SPORTDiscus were systematically searched on May 9, 2020, and updated on September 14, 2021. Inclusion criteria were based on PICO and included healthy athletes and active adults of any sex (≤40 years), performing supervised sSIT (≤10 s of "all-out" and non-"all-out" efforts) of at least 2 weeks, with a minimum of 6 sessions. As a comparator, a non-sSIT control group, another high-intensity interval training (HIIT) group, or a continuous training (CT) group were required. A total of 18 studies were deemed eligible. The estimated SMDs based on the random-effects model were -0.56 (95% CI: -0.79, -0.33, p < 0.001) for V̇O2 max, -0.43 (95% CI: -0.67, -0.20, p < 0.001) for aerobic performance, and -0.44 (95% CI: -0.70, -0.18, p < 0.001) for anaerobic performance after sSIT vs. no exercise/usual training. However, there were no significant differences (p > 0.05) for all outcomes when comparing sSIT vs. HIIT/CT. Our findings indicate a very high effectiveness of sSIT protocols in different exercise modes (e.g., cycling, running, paddling, and punching) to improve V̇O2 max, aerobic, and anaerobic performances in physically active young healthy adults and athletes.

Acute and Delayed Effects of Time-Matched Very Short "All Out" Efforts in Concentric vs. Eccentric Cycling.

BACKGROUND: To the authors' knowledge, there have been no studies comparing the acute responses to "all out" efforts in concentric (isoinertial) vs. eccentric (isovelocity) cycling. METHODS: After two familiarization sessions, 12 physically active men underwent the experimental protocols consisting of a 2-min warm-up and 8 maximal efforts of 5 s, separated by 55 s of active recovery at 80 rpm, in concentric vs. eccentric cycling. Comparisons between protocols were conducted during, immediately after, and 24-h post-sessions. RESULTS: Mechanical (Work: 82,824 ± 6350 vs. 60,602 ± 8904 J) and cardiometabolic responses (mean HR: 68.8 ± 6.6 vs. 51.3 ± 5.7% HRmax, lactate: 4.9 ± 2.1 vs. 1.8 ± 0.6 mmol/L) were larger in concentric cycling (p < 0.001). The perceptual responses to both protocols were similarly low. Immediately after concentric cycling, vertical jump was potentiated (p = 0.028). Muscle soreness (VAS; p = 0.016) and thigh circumference (p = 0.045) were slightly increased only 24-h after eccentric cycling. Serum concentrations of CK, BAG3, and MMP-13 did not change significantly post-exercise. CONCLUSIONS: These results suggest the appropriateness of the eccentric cycling protocol used as a time-efficient (i.e., ~60 kJ in 10 min) and safe (i.e., without exercise-induced muscle damage) alternative to be used with different populations in future longitudinal interventions.