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Is heart rate a convenient tool to monitor overreaching?

Submitted by Dave on Mon, 08/17/2009 - 18:17

Is heart rate a convenient tool to monitor overreaching? A systematic
review of the literature
LAURENT BOSQUET 1*, SAID MEKARI 1, DENIS ARVISAIS 1 and ANDRE E
AUBERT 2
Br J Sports Med. Published Online First: 28 February 2008.
doi:10.1136/bjsm.2007.042200

Abstract
Objective: A meta-analysis is conducted on the effect of overload
training on resting heart rate, submaximal and maximal exercise heart
rates and on heart rate variability, to determine whether these
measures can be used as valid markers of overreaching.

Methods: Six databases were searched using relevant terms and
strategies. Criteria for study inclusion were: participants must be
competitive athletes; an increased training load intervention must be
employed; all necessary data to calculate effect sizes must be
available. An arbitrary limit of two weeks was chosen to make the
distinction between short term and long term interventions. Dependant
variables were heart rate and heart rate variability (during supine
rest). Pre–post intervention standardized mean differences (SMD) in
heart rate or heart rate variability were calculated, and weighted
according to the within– group heterogeneity to develop an overall
effect.

Results: In these competitive athletes, short term interventions
resulted in a moderate increase in both resting heart rate (SMD=0.55;
p=0.01) and LF/HF (SMD=0.52; p=0.02), and a moderate decrease in
maximal heart rate (SMD=-0.75; p=0.01). Long term interventions
resulted in a small decrease of heart rate during submaximal (SMD=-
0.38; p=0.006) and maximal exercise (SMD=-0.33; p=0.007), without
alteration of resting values.

Conclusion: The small to moderate amplitude of these alterations
limits their clinical usefulness, since expected differences may fall
within day-to-day variability of these markers. Consequently, the
correct interpretation of heart rate or heart rate variability
fluctuations during the training process requires the comparison with
other signs and symptoms of overreaching to be meaningful.