Abstract
We aimed to characterize cardiac-autonomic responses to a 13-day preseason camp
in the heat among an American college football team. Players were categorized as
linemen (n=10) and non-linemen (n=18). RHR, natural logarithm of
the root-mean square of successive differences multiplied by twenty (LnRMSSD),
and subjective wellbeing (LnWellness) were acquired daily. Effect
sizes±90% confidence interval showed that for linemen, LnRMSSD
decreased (moderate) on day 2 (71.2±10.4) and increased (moderate) on
day 12 (87.1±11.2) relative to day 1 (77.9±11.2) while RHR
decreased (small–moderate) on days 6, 7, and 12
(67.7±9.3–70.4±5.5 b∙min-1) relative to day 1
(77.1±10.1 b∙min-1). For non-linemen, LnRMSSD increased
(small–large) on days 3–5, 7, 12, and 13
(83.4±6.8–87.6±8.5) relative to day 1 (80.0±6.5)
while RHR decreased (small–large) on days 3–9, 12, and 13
(62.1±5.2–67.9±8.1 b∙min-1) relative to day 1
(70.8±6.2 b∙min-1). Decrements in LnWellness were observed on
days 4–10 and 13 for linemen (moderate) and on days 6–9, 12, and
13 for non-linemen (small–moderate). Despite reductions in LnWellness,
cardiac-autonomic parameters demonstrated responses consistent with
heat-acclimation, which possibly attenuated fatigue-related decrements.
Key words
autonomic - cardiac-parasympathetic - sports science - cardiovascular - adaptation
