Parasympathetic reactivation after repeated sprint exercise

Parasympathetic reactivation after repeated sprint exercise
Martin Buchheit,1 Paul B. Laursen,2 and Saïd Ahmaidi1

Am J Physiol Heart Circ Physiol 293: H133-H141, 2007. First published
March 2, 2007; doi:10.1152/ajpheart.00062.2007
0363-6135/07 $8.00

Submitted 16 January 2007 ; accepted in final form 26 February 2007

The purpose of this study was to examine the effects of muscular
power engagement, anaerobic participation, aerobic power level, and
energy expenditure on postexercise parasympathetic reactivation. We
compared the response of heart rate (HR) after repeated sprinting
with that of exercise sessions of comparable net energy expenditure
and anaerobic energy contribution. Fifteen moderately trained
athletes performed 1) 18 maximal all-out 15-m sprints interspersed
with 17 s of passive recovery (RS), 2) a moderate isocaloric
continuous exercise session (MC) at a level of mean oxygen uptake
similar to that of the RS trial, and 3) a high-intensity intermittent
exercise session (HI) conducted at a level of anaerobic energy
expenditure similar to that of the RS trial. Subjects were
immediately seated after the exercise trials, and beat-to-beat HR was
recorded for 10 min. Parasympathetic reactivation was evaluated
through 1) immediate postexercise HR recovery, 2) the time course of
the root mean square for the successive R-R interval difference
between successive 30-s segments (RMSSD30s) and 3) HR variability
vagal-related indexes calculated for the last 5-min stationary period
of recovery. RMSSD30s increased during the 10-min period after the MC
trial, whereas RMSSD30s remained depressed after both the RS and HI
trials. Parasympathetic reactivation indexes were similar for the RS
and HI trials but lower than for the MC trial (P < 0.001). When data
of the three exercise trials were considered together, only anaerobic
contribution was related to HR trial-derived indexes. Parasympathetic
reactivation is highly impaired after RS exercise and appears to be
mainly related to anaerobic process participation.