Acute Physiological, Metabolic and Perceptual Responses to different High-Intensity Interval Training formats

INTRODUCTION Research in sport and exercise science suggested that both placebo and nocebo can influence sport performance (1), with effect ranging from small to moderate (2). Most of studies proposed as treatment nutritional ergogenic aids or peripheral stimulation. However, a more ecological approach lowered into a conventional training session, could exploit some parts of the training itself to administer placebo/nocebo effect. The aim of the present study was to test the effect on the running performance of a placebo/nocebo treatment consisting in conditioning manipulation plus verbal suggestion. METHODS Thirty-nine active young students (mean age 22±0.9) were randomly assigned to CONTROL group, PLACEBO group and NOCEBO group. The experiment consisted in 3 sessions. During TEST Session participants performed the Cooper test to evaluate the cardiorespiratory fitness. During SESSION 1, they performed a high intensity interval training (HIIT) protocol till exhaustion (30s all-out, with 2 min of passive recovery) preceded by a conventional warm-up (20min, running and dynamic stretching). During SESSION 2, warm up consisted in the FIFA 11+ (20min, running and balance exercises) (3), and was used as conditioning treatment. Participants’ expectancy about warm-up efficacy in not-changing/improving/worsening the following HITT performance was manipulated through verbal suggestion in CONTROL/PLACEBO/NOCEBO groups. At last, during the HIIT rest-period a surreptitious manipulation, consisting in none/positive/negative verbal feedback about the current performance, was administered to CONTROL/PLACEBO/NOCEBO group. The time to exhaustion (TTE) and total running distance (TRD) were considered as performance outcome. The rate of perceived exertion (RPE), maximal heart rate (HR) and blood lactate ([LA+]) were used to determine whether participants reached the exhaustion. ANOVA was applied to evaluate normally-distributed parameters, whilst non parametric analysis were applied to not-normally distributed data. RESULTS TTE and TRD values of the PLACEBO group significantly increased in SESSION 2 with respect to SESSION 1 whilst they significantly decreased in NOCEBO group (p<0.05 and p<0.01, respectively). Further, TTE (p<0.05) and TRD (p<0.01) in SESSION 2 of the PLACEBO group was significantly higher than those of NOCEBO group. No differences appeared in the CONTROL group. No differences among groups and session were found in RPE, HR and [LA+]. CONCLUSION The innovative placebo/nocebo treatment proposed in this study succeeded to improve/worsen the running performance of active young adult. These results provide insight on the interaction between the athlete’s cognitive domain and the running performance and pave the way for the application of combined cognitive/motor strategies during training.

Purpose: The aim of this study was to compare the acute cardiorespiratory and metabolic effects induced by a High-Intensity Continuous Training (HI-CT) and three High-Intensity Interval Training regimes (HIITs) in young active students. The assessment of internal training load through the rate of perceived exertion (RPE) at iso-time was also a focus. Methods: Fifteen active university students (age: 21.0±1.1 ys, height: 1.74±0.9 m, weight: 64.8±12.9 kg, VO2max 48.1±7.5 mL∙kg-1∙min-1) performed an incremental treadmill test to assess VO2max and maximal aerobic speed (MAS). Then, each participant performed, on testing sessions, separated by a minimum of 72 h and in a randomized order, one HI-CT session at 95% MAS for 8 minutes and three different HIIT sessions (10s-20s, 30s-30s, 50s-30s) with a work phase at 95% MAS and an active recovery at 40% MAS for 16 minutes. Oxygen consumption (VO2), heart rate (HR), time spent near or above 90%VO2max (T@90%VO2max) and blood lactate concentration ([La]+) were measured. The rating of perceived exertion (RPE), by the Borg’s CR 10 scale, was used to assess the subjective level of fatigue experienced at the end of each testing session. Results: The statistical analysis revealed that VO2peak, HRpeak, T@90%VO2max, and RPE values in 10-20 HIIT were significantly lower compared to 30-30 and 50-30 HIIT regimes (p always <0.001). In HI-CT session VO2peak, HRpeak, T@90%VO2max were significantly higher than in 10-20 and 30-30 sessions (p<0.0001 and p<0.05). Blood lactate values were significantly higher in HI-CT and in 50-30 and 30-30 HIITs, compared to 10-20 protocol. Finally, internal workload in HI-CT and 50-30 HIIT was significantly higher than those in 30-30 (p<0.01) and 10-20 (p<0.0001) HIIT sessions. Conclusions: Our results show that in active young subjects a HI-CT and a long work interval HIIT regime (50-30) represent an optimal training stimulus to elicit higher physiological and metabolic responses compared to short work interval HIIT regimes (30-30 and 10-20), being the most effective for stressing both the aerobic and anaerobic energy systems. Coaches can choose and balance the level of aerobic/anaerobic energy requirements and neuromuscular engagement associated with the three HIIT regimes and a HI-CT protocol based on the expected physiological and metabolic adaptations as well as neuromuscular characteristic and ability level of the athlete/subject individual profile.