Effects of intensity distribution changes on performance and on training loads quantification

Abstract

The present study analyses the effects of the high-intensity distribution change within sessions on physical performance and on training loads (TL) provided by quantification methods based on heart rate (HR) and on whole body indicators of exercise-induced physiological stress. Fourteen trained physical education students (21.9±1.2 years, 68.3±7.9 kg, 180±7.3 cm) performed two sessions with the same intensities, volumes and pauses but differing in the efforts' intensity distribution: one was composed of exercises dissociating the intensities (12 repetitions of 30 m sprints then 12 min interval runs) and the second mixed the intensities (30 m sprint followed by 60 s rest and 2 runs of 15 s - 15 s at 100% and 50% of maximal aerobic velocity - MAV). Session TL was calculated using methods based on heart rate zones, training impulse, ratings of perceived exertion (session RPE) and endurance limit. Session-induced fatigue was observed using performances in repeated sprints and counter-movement jumps. The heart rate zone method provided higher TL for the mixed session (p=0.007), while training impulse described similar TL for the two sessions (p=0.420). The endurance limit method showed borderline significantly higher TL in dissociated sessions (p=0.058) and session RPE provided similar but the largest differences between sessions' TL (p=0.001). The dissociated session induced larger losses in counter-movement jumps (p=0.010) but lower speed decreases in sprints (p=0.007). Change in intensity distribution within sessions induced contradictory effects on performances and on TL quantification according to the method used. When high intensities are programmed, methods based on heart rate may present limitations for TL quantification, as such methods based on whole body indicators of exercise-induced physiological stress should be preferred.

Keywords: Heart rate; Methodology; Physical conditioning; Rating of perceived exertion; Training programmes.

FIG. 1

Study design for weeks 1, 2 and 3. In week 1, testing sessions occurred (test 1 and test 2) and in weeks 2 and 3 dissociated and mixed sessions were performed. Counter-movement jumps (CMJ) were performed at the beginning and the end of the training sessions. Dissociated session: twelve 30 m sprints (pause of 90 s between sprints); 6 min pause; 12 min of interval exercise alternating 15 s at 100% of MAV and 15 s at 50% of MAV. Mixed session consisted in 12 repetitions of a set composed of: 30 m maximal sprint; 60 s pause; 2 runs of 15 s-15 s at 100% and 50% of MAV; 60 s pause.

FIG. 2

Ratings of perceived exertion over the dissociated (black dots) and mixed sessions (grey squares), the sessions terminated at 36 min and + 30 min corresponded to the record performed 30 min after the session end. *: Significant differences between the two sessions. At all time points of a given training session a time effect was observed (except from end to +30 min records); for clarity of the figure, this time effect was not graphically presented.

FIG. 3

Box plots for training loads in dissociated and mixed sessions using endurance limit based method (WER, up-left), training impulse method (TRIMP, down left), session ratings of perceived exertion method (RPE, up-right) and summated heart rate zone method (SHRZ, down right). *: Significant differences between the two sessions; TL differences for the WER method were on the verge of statistical significance (p=0.058). Continuous and horizontal black lines for medians, and black dots for outliers.