Heart Rates, Cardiac Arrhythmia, Lactate Levels and Catecholamine Excretions in CHD Patients During Cross-Country Skiing

Abstract

We examined cross-country skiing-related strain in 10 less experienced postinfarction patients, performing a skiing test, covering a distance of approximately 7 km in 90 min. Heart rates, cardiac arrhythmia, lactic acid levels and catecholamine excretions were determined as strain indicators. The patients' exercise capacity, estimated during graded ergometric cycling, was 2.1±0.4 watts·kg^-1, indicating a nearly age-appropriate submaximum performance ability. They had suffered myocardial infarction 2.8±0.7 years previously, participated regularly in a rehabilitation program for at least one year, and they did not show coronary insufficiency or significant cardiac dysrhythmias during laboratory testing under their usual medications. They went cross-country skiing during a 4-day instruction period and subsequently performed a crosscountry skiing test on the 5th day. Mean skiing-related heart rates (124±9 bpm) and adrenaline excretions (124±88 pmol·min^-1) corresponded on average to an exercise level of 1.85-2.0 watts·kg^-1 during laboratory testing, and mean noradrenaline excretions (586-343 pmol·kg^-1) and lactate concentrations (3.83 ±2.18 mmol·^-1) to a level of 1.48-1.73 watts·kg^-1. Cardiac dysrhythmias were observed in a moderate number of 6-8 SVES, 9 to 12 VES and 4 to 7 couplets of VES per 1000 beats during cross-country skiing. The present results point to a comparatively high cardiovascular strain in less experienced postinfarction patients during a cross-country skiing test at an intensity level thought to be moderate.

Key words

CHD patients - cross-country skiing