Age as a poor predictor of blood-lactate and heart-rate responses during club-level orienteering

This study investigated heart-rate (HR) and lactate responses of 31 club-level orienteers (age 23-68 years) during competitions in technically easy (TE) and technically difficult (TD) terrain. HR was monitored throughout the events, and capillary-blood samples for lactate analysis were taken at a midpoint and at the finish. HR and lactate responses were relatively consistent within and between events. Orienteering speed and mean lactate levels were lower in the more complex terrain (TE 5.6 vs. TD 4.1 mmol/L). Age was not a predictor of lactate values. The peak HR for both events was 175 ± 10 beats/min and decreased with age by 2–5 beats · min · decade−1. Mean HR was TE, 162 ± 11, and TD, 156 ± 14 beats/min, and did not decline with age. Participants older than 45 years frequently displayed peak and mean HR responses exceeding those predicted from commonly applied age-related algorithms.