Similar Anaerobic and Aerobic Adaptations After 2 High-Intensity Interval Training Configurations: 10:5 s vs. 20:10 s Work-to-Rest Ratio

Sprint Interval Training on Stationary Air Bike Elicits Cardiorespiratory Adaptations While Being Time-Efficient

ABSTRACT

Moghaddam, M, Cervantes, M, Cheshier, B, and Jacobson, BH. Sprint interval training on stationary air bike elicits cardiorespiratory adaptations while being time-efficient. J Strength Cond Res 37(9): 1795-1801, 2023-Sprint interval training (SIT) refers to a set of brief intermittent exercises that are performed at maximal intensity. This study compared the effects of 2 SIT protocols (e.g., 10-5-SIT and 20-10-SIT) vs. moderate-intensity continuous training (MICT) on cardiovascular adaptations, using stationary air bikes. Thirty-two recreationally active individuals were randomly assigned to the 3 performance groups, such as 10-5-SIT (n = 11), 20-10-SIT (n = 10), and MICT (n = 11), to train 3 days per week for 4 weeks. Moderate-intensity continuous training included 30 minutes of cycling at 75% of maximal heart rate reserve, whereas the SIT protocols consisted of 3 sets of 8 intervals at all-out intensity. The 10-5-SIT and 20-10-SIT were performed with 10-second work:5-second rest and 20-second work:10-second rest, with 2.5- and 5-minute recovery periods between sets, respectively. A ramp protocol was used before and after the intervention via cycle ergometer to assess aerobic performance. Time to exhaustion (TTE), absolute V̇o2max (A-V̇o2max), relative V̇o2max (R-V̇o2max), and metabolic equivalents (METs) were measured and analyzed with 2-way mixed factorial analyses of variance (ANOVAs). In addition, total work (TW) during 12 sessions were recorded and analyzed with 1-way ANOVA. Significant (p < 0.05) differences were found for TW (10-5-SIT: 907.3 ± 332.0, 20-10-SIT: 1230.0 ± 188.1, and MICT: 2263.0 ± 896.9 calories) between groups. A significant main effect of time was observed for 10-5-SIT, 20-10-SIT, and MICT (p < 0.05) in TTE (increased by 7.3, 8.7, and 8.2%), A-V̇o2max (increased by 13.0, 11.8, and 13.6%), R-V̇o2max (increased by 12.6, 12.1, and 14.8%), and METs (increased by 12.7, 12.3, and 14.9%), respectively. Despite less volume and duration, both SIT protocols induced cardiorespiratory adaptations similar to MICT. These findings suggest that performing SIT on a stationary air bike is valuable because of time-efficiency and cardiorespiratory adaptations.

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 seconds 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, SPORTDiscus were systematically searched on the 9^th of May 2020 and updated on the 14^th of September 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 was 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, punching) to improve V̇O₂ max, aerobic and anaerobic performances in physically active young healthy adults and athletes.

[Lactate changes during mobilization of intensive care patients : A retrospective observational study]

BACKGROUND

For intensive care patients the return to normal life is usually a long and strenuous journey. In addition to the severity of the underlying disease, possible comorbidities, sedation and pain management as well as the use of various drugs together with the length of stay in the intensive care unit are factors that strongly influence the course of early rehabilitation and thus the functional outcome. Intensive care patients in particular are exposed to extreme stress during mobilization and often reach their cardiopulmonary stress limit. In order to determine such limits, lactate measurement is used in the performance diagnostics of athletes.

METHODS

In a retrospective study 20 intensive care patients were mobilized up to their subjective maximum load capacity during physiotherapy (sitting on the edge of the bed n = 6, standing n = 12 and walking n = 2). The lactate value was determined from the routine arterial blood gas analysis and then an attempt was made to establish a correlation between the subjectively perceived change in exercise load (Borg CR10) and the changes in lactate measurements.

RESULTS

Changes in the sense of an increase in stress occurred in both in the Borg scale and in the lactate measurements. The subjective maximum load capacity increased on average by 4.85 points (p = 0.13, 95% confidence interval, CI 4.58-5.12). In addition, a significant mean increase in lactate by 10.8 mg/dl (p < 0.001, 95% CI 9.73-11.87) was observed. No positive correlation between the load-induced changes in Borg values and the development of lactate values was shown (Pearson correlation: r = 0.123).

CONCLUSION

The subjective load increase in the Borg CR10 observed in all 20 intensive care patients included in the study and the associated significant increase in lactate after mobilization, suggest that an efficient load in the sense of a training-desired supercompensation was achieved through mobilization. The tendency towards a correlation between the changes in Borg CR10 and the lactate values can be interpreted as an indication that the development of lactate values can also be used in intensive care patients to avoid overloading of patients in early rehabilitation.

Muscular morphological adaptations of two whole-body high intensity interval training configurations

BACKGROUND

High-intensity intermittent training (HIIT) has increased in popularity due to being time-efficient mode of exercise. Previous HIIT studies have mainly focused on percentage of fat loss, fat mass loss, and weight loss. However, enhancing muscle protein synthesis induced by HIIT that results in muscular morphological adaptations is a potential benefit of HIIT. This study compared the effects of two HIIT protocols on muscular morphological adaptations.

METHODS

Thirty-four recreationally active participants were randomly assigned to 10-5-HIIT and 20-10-HIIT to complete 6 sets of 6 intervals. The 10-5-HIIT and 20-10-HIIT protocols were performed with 10s:5s and 20s:10s exercise-to-rest ratios and provided with 1- and 2-min recovery periods between sets, respectively. Muscle cross-sectional area (mCSA) and echo intensity (EI) of the rectus femoris (RF) and vastus lateralis (VL) were assessed via B-mode ultrasonography before and after intervention. Two-way mixed factorial ANOVAs were used for analyses.

RESULTS

The 10-5-HIIT and 20-10-HIIT groups significantly (P<0.05) increased RF mCSA (change (Δ)=0.4±0.8 cm2, 8.0%; Δ=0.5±0.8 cm2, 5.5%) and VL mCSA (Δ=1.2±1.6 cm2, 9.0%; Δ=2.20±1.4 cm2, 10.4%), respectively. No significant (P>0.05) change was observed for the EI of the RF and VL.

CONCLUSIONS

Whole-body HIIT can be a time-efficient exercise modality to elicit muscular morphological adaptations in the RF and VL muscles. The 10-5-HIIT protocol induced benefits comparable to those of the 20-10-HIIT, while it reduced the total exercise time by 50%.