Maximal rate of increase in heart rate during the rest-exercise transition tracks reductions in exercise performance when training load is increased

ObjectivesHeart rate kinetics are faster in well-trained athletes at exercise onset, indicating sensitivity to training status, but whether they track performance changes due to changes in training load is unknown.DesignRandomised, counterbalanced, cross-over.Methods17 cyclists completed two weeks of light and two weeks of heavy training. The day after each training period heart rate was recorded during 5 min cycling at 100 W to determine the maximal rate of heart rate increase. Participants then performed a 5 min cycle time-trial after which heart rate recovery was determined.ResultsWork during 5 min cycle time-trial decreased 3.5% (P < 0.04) in participants (n = 8) who increased training load (completed light training then heavy training) and, although maximal rate of heart rate increase did not change (P = 0.27), within-individual changes in work were correlated with changes in maximal rate of heart rate increase (r = 0.87, P = 0.005). Work during 5 min cycle time-trial increased 6.5% (P < 0.001) in 9 participants who decreased training load (completed heavy training then light training) and maximal rate of heart rate increase increased 28% (P = 0.002) but the changes in maximal work were not related to changes in rate of heart rate increase (r = 0.32, P = 0.40). Heart rate recovery tended to track changes in 5 min cycle time-trial work following increases and decreases in training load (r = 0.65–0.75, P = 0.03–0.08).ConclusionsMaximal rate of heart rate increases during cycling at 100 W tracks reductions in exercise performance when training load is increased, but not performance improvements when training loads are reduced. Maximal rate of heart rate increase may be a useful adjunct to heart rate recovery for tracking changes in exercise performance.