Square-wave endurance exercise test (SWEET) for training and assessment in trained and untrained subjects. I. Description and cardiorespiratory responses.

A new 45 min Square-Wave Endurance Exercise Test (SWEET) performed on a cycle ergometer and designed for endurance training was studied in 43 normal subjects: Untrained (U), twelve women and seven men and Trained (T), eight women and 16 men. Among them seven were elite sportsmen (E). Preliminary measurements were made of VO2 max by constant power and Maximal Tolerated Power (MTP) in a progressive test (+ 30 W/3 min). To the SWEET's base, established as a % of individual MTP, a peak of 1 min at MTP was added every 5 minutes. Maximum Intensity of Endurance during the SWEET (MIE45) is defined by both maximal heart rate (HR) at the end of the test and the impossibility of maintaining 5% above the percent MTP of the MIE45 for 45 min. Exhaustion was reached at the end of the MIE45, which could be expressed as % MTP, as total energy expenditure (TEE) in liters of O2, or as total mechanical work (TMW) in kiloJoules per kg of weight (kJ . kg-1). VE, VCO2, VO2 and HR were continuously measured. VO2 max, TMW and % MTP were significantly higher in T than in U subjects. The E subjects show the highest values of those parameters. TMW and TEE were well correlated (r = 0.992, p less than 0.001, n = 43) indicating good efficiency. TMW in T (r = 0.453) and in E men (r = 0.442) were however less well correlated to the VO2 max. MIE45 therefore gives different information in the evaluation of "endurance capacity" at the time of measurement than that provided by VO2 max. Because of the high TEE per session it could be useful for endurance training of T and U subjects.