Analysis of Heart Rate Variability after a Ranger Training Course

Abstract

We studied the effects of prolonged physical activities on resting heart rate variability (HRV) during a training session attended by 23 cadets of the French military academy. This course lasts 1 month and is concluded by a 5-day field exercise simulation with physical and psychological stress. Data collection took place before (B) and immediately at the end (E) of the course. It included HRV recordings during a stand test (5 minutes lying down and 5 minutes standing), with a Polar R-R monitor, followed by blood sampling to assay plasma testosterone. The results (B and E) showed that the testosterone level fell by approximately 28.6 +/- 7%, indicating a high level of fatigue. During the stand test, the total power (TP) of the HRV spectrum increased in a supine position. The TP of B was 5,515.7 ms2 (SE, 718.4) and of E was 13018.9 ms2 (SE, 2,539.2; p < 0.001). High-frequency (HF) normalized values increased and low-frequency (LF) normalized values fell, regardless of position (HF normalized values and LF normalized values: supine, p < 0.01, p < 0.05; standing, p < 0.05, p < 0.01, respectively). LF:HF ratio fell 66.2 (SE, 12.9%; p < 0.01) in a lying position. During the time-domain analysis of HRV, differences between adjacent normal R-R intervals more than 50 milliseconds, expressed as a percentage, and differences between the coupling intervals of adjacent normal RR intervals increased in the lying position (p < 0.001). These results as a whole suggest that parasympathetic nervous system activity increases with fatigue.

Heart Rate and Autonomic Balance During Stand Tests Before and After Fighter Combat Missions

“…These modifi cations of HRV components may result in impairment of physical and mental performance ( 21 ). The same results have already been observed in chronic situations, such as overtraining syndrome or exhaustion after a Ranger training course ( 10 ). Changes in HRV are also reported among drivers of motor vehicles after long test drives.…”

“…In a previous experiment, we showed that in-fl ight HR increased during high compared to low mental workload fl ight phases ( 3,4 ). Moreover, Perini et al ( 20 ) suggested that HRV power spectral analysis can provide a quantitative assessment of cardiac autonomic activities in numerous physiological conditions and previous studies by our laboratory have demonstrated its interest in similar aeronautical domains and during military ranger training courses ( 10 ). According to Backs et al ( 1 ), autonomic components provide a precise assessment of mental workload.…”

Heart Rate Variability

“…The findings represent physiological evidence that magnitopuncture may reduce mental fatigue in healthy drivers [105]. Jouanin et al have studied the effects of prolonged physical activities on resting heart rate variability (HRV) during a training session attended by 23 cadets of the French military academy [106]. These results as a whole suggest that parasympathetic nervous system activity increases with fatigue.…”

Die uitwerking van ’n intensiewe afrigtingsprogram op die kardiostresindeks

“…Jouanin et al (2004) verwys na 'n afname in die sistoliese bloeddruk (pre-: 126 mmHg ± 3 mmHg, post-: 111 mmHg ± 4 mmHg) en diastoliese bloeddruk (pre-: 76 mmHg ± 3 mmHg, post-: 67 mmHg ± 3 mmHg) by militêre rekrute ná 'n fisiek en sielkundig strawwe vyf week lange kursus vir Amerikaanse berede soldate of 'rangers'. Moontlike meganismes wat veroorsaak dat oefening bloeddruk verlaag, kan onder meer neurohormonale response en vaskulêre en strukturele aanpassings insluit (Pescatello et al 2004).…”

“…Ofskoon talle studies in ooreenstemming is met die gevolgtrekking dat verbeterende vagale modulering voordelige kardiovaskulêre uitwerking het, is daar nog geen konsensus oor die mate van verhoogde parasimpatiese tonus wat vereis word ten einde genoegsame beskerming van die hart teweeg te bring nie (Jouanin et al 2004).…”