Reversed drift in heart rate but increased oxygen uptake at fixed work rate during 24 h ultra-endurance exercise.

Mattsson, C. MikaelKarolinska Institutet,Gymnastik- och idrottshögskolan,Björn Ekbloms forskningsgrupp (författare)

In this paper we report a reversed drift in heart rate (HR) but increased oxygen uptake (VO(2)) during ultra-endurance exercise. Nine well-trained male athletes performed 24-h exercise in a controlled laboratory setting, with alternating blocks of kayaking, running and cycling. Each block included 110 min of exercise and 10 min of rest, with an average work intensity of approximately 55% of respective VO(2peak). Blood samples were taken and HR and VO(2) measured every 6th hour during steady-state cycling at fixed work rate. As assumed HR was increased at 6 h by 15 +/- 6 beats/min compared with initial level (0 h). Thereafter the drift did not progress continuously, but instead unexpectedly returned toward initial values, although the plasma levels of catecholamines increased continuously during exercise. VO(2) was increased by 0.22 +/- 0.15 L/min (10%) at 6 h and 0.37 +/- 0.18 L/min (17%) at 12 h compared with 0 h, and thereafter remained stable. This implies an increased oxygen pulse (VO(2)/HR) by approximately 10% at the last half of the 24-h exercise compared with 0 h. Consequently, sole use of HR would give inaccurate estimates of exercise intensity and energy expenditure during endurance exercise lasting more than 6 h, and different patterns of cardiovascular drift need to be taken into account.

Enqvist, Jonas KGymnastik- och idrottshögskolan,Björn Ekbloms forskningsgrupp(Swepub:gih)jonase (författare)
Brink-Elfegoun, ThibaultGymnastik- och idrottshögskolan,Björn Ekbloms forskningsgrupp (författare)
Johansson, Patrik HGymnastik- och idrottshögskolan,Björn Ekbloms forskningsgrupp (författare)
Bakkman, LindaKarolinska Institutet,Gymnastik- och idrottshögskolan (författare)
Ekblom, BjörnGymnastik- och idrottshögskolan,Björn Ekbloms forskningsgrupp(Swepub:gih)bjorne (författare)
Gymnastik- och idrottshögskolanBjörn Ekbloms forskningsgrupp (creator_code:org_t)

Ingår i:Scandinavian Journal of Medicine and Science in Sports: Wiley20:2, s. 298-3040905-71881600-0838

Av författaren/redakt...: Mattsson, C. Mik ...; Enqvist, Jonas K; Brink-Elfegoun, ...; Johansson, Patri ...; Bakkman, Linda; Ekblom, Björn

Om ämnet

MEDICIN OCH HÄLSOVETENSKAP: MEDICIN OCH HÄLS ...; och Medicinska och f ...; och Fysiologi

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