The Effect of Training Status on Critical Power and Work Prime

Critical Power (CP) represents a threshold of sustainable endurance exercise; work prime (W’) represents the amount of metabolic disturbance one is capable of enduring above CP before exhaustion. CP increases with endurance training, but it is unclear how much of this can be explained by differences in muscle mass and body mass. PURPOSE: Characterize relationship between training status and CP and W when normalized for body and muscle mass. METHODS: We recruited 23 individuals (10 untrained individuals; 7 female, 3 male age= ~23.8yrs and 13 trained individuals; 7 female, 6 male, age= ~25.8yrs). A graded VO2max test was conducted on a cycle ergometer; max work rate (WRmax) was defined as the maximum power output reached during VO2max. The subjects performed a series of intense time-to-task failure tests on the cycle ergometer on two separate visits at different percentages of the WRmax. The relationship between time and work for the various time-to-task failure tests determined CP and W’ through linear regression (work-time method). After CP had been determined, the subjects preformed a final time-to-task-failure test set at ~95% of the determined CP. RESULTS: Absolute CP was notably higher in trained individuals (189.71 ± 39.88 watts) than untrained (146.62 ± 46.85 watts) (pCONCLUSION: Training status appears to affect absolute CP, CP normalized by total body mass and leg lean mass. Furthermore, these trained individuals were able to sustain a power output near CP for a greater period of time

Do Sex Differences Exist in Critical Power and W’?

Among world-class athletes, biological males tend to be faster and stronger than biological females, in part due to differences in body composition, such as lower body fat percentage and increased muscle mass. Critical power (CP) represents the highest intensity that elicits compensable and sustainable disturbances to homeostasis, while W’ is the amount of work and its associated metabolic disturbance that can be tolerated above CP. Together, CP and W’ strongly influence endurance performance. PURPOSE: To determine if sex-based differences in CP and W’ exist when normalizing for lean muscle mass. METHODS: We recruited 20 non-endurance trained individuals (10 female and 10 male, age= ~25.7yrs). VO2max was first determined through a graded exercise test on a cycle ergometer. The subjects then performed time to task failure tests at different percentages of their maximum work rate. CP and W’ were determined by linear regression of the relationship between time and work for the various tests to task failure. RESULTS: Leg lean mass was approximately 37% less in females than males (pAbsolute W’ was approximately 64% less in females than males (

Impact of High Intensity Interval Training Versus Moderate Intensity Continuous Training on Critical Power

Critical Power (PCRIT) is the greatest power that a person can sustain for prolonged periods of time while maintaining steady-state, submaximal aerobic conditions. Work-prime (W’) is the amount of work that can be tolerated when exercising in non-steady-state conditions above PCRIT. PURPOSE: Compare the effect of equal amounts of moderate intensity continuous training (MICT) and high intensity interval training (HIIT) on PCRIT and W’. METHODS: Twenty-two (10 female) untrained, young adults completed 8 weeks of cycling training (40 minutes, 3x per week) administered as either MICT (44% max power achieved during a graded exercise test; PGXT) or HIIT (4 bouts at 80% PGXT for 4 minutes with recovery intervals between). PCRIT, W’ and other physiological variables were determined before and after training. RESULTS: PCRIT significantly increased in both groups, but to a greater extent in the HIIT group (MICT: 15.7 ± 3.1% vs. HIIT: 27.5 ± 4.3%; P=0.04). W’ was not consistently impacted by training (P=0.76). The training-induced change in PCRIT was not significantly related to the training-induced change in V̇O2MAX. The training-induced increase in PCRIT was related to how intense the training was relative to PCRIT, with those performing the same workout at a greater % PCRIT exhibiting greater training-induced increases in PCRIT (R2=0.49, PCONCLUSION: HIIT elicits approximately twice the increase in PCRIT than an equal amount of MICT in untrained young adults. Training-induced increases in PCRIT are not dependent upon changes in V̇O2MAX. Exercise may be more effectively prescribed and described relative to PCRIT, rather than V̇O2MAX or PGXT