Enhanced Strength, Power, Work Capacity, and Fatigue Resistance in High Intensity Functional Training Athletes
Authors: Green Edward S , Williams Ewan R , McCully Kevin K , Jenkins Nathan T 
Published: June 2021

Measures of aerobic capacity, strength, fatigue, and power in athletes who specialize in either strength or endurance are relatively well understood. However, these measures in athletes who participate in high intensity functional training (HIFT) are comparatively unknown.PURPOSETo assess differences in aerobic capacity (VO2max), peak power (PP), end power (EP), strength (N.m), and fatigue (%change) in recreational athletes from Powerlifting and Olympic Lifting (STR), Cross Country (END) and HIFT backgrounds.METHODSTwenty‐one individuals from the three different training backgrounds were recruited (STR = 7, END = 7, HIFT = 7). Participants completed an incremental ramp, 30W/minute maximal cycle ergometer test to determine VO2max and gas exchange threshold (GET), and a 3‐minute all out sprint cycling test (3MAOT) to determine peak power (PP) and end power (EP). PP was determined as the maximal power out during the first 6s of the 3MAOT, and EP was calculated as the average power output during the last 30s. To determine strength, participants completed a maximal voluntary contraction (MVC) of the knee extensors on a Biodex at 90°, 75°, and 60° of knee flexion. A triaxial accelerometer was placed on the right vastus lateralis to measure fatigue as the %change in movement during 11‐minutes of continuous electrical stimulation separated by 30‐seconds of rest at the 9‐minute mark. Electrical stimulation consisted of doublets at a 5Hz train rate. Accelerometry data were digitally filtered with low‐pass filter at 40Hz cut off (4th order; Butterworth). Data were analyzed using a repeated measures ANOVA with results presented as mean and SD.RESULTSVO2max was significantly different between all groups (p < 0.01). PP was significantly higher in STR and HIFT compared to END (p < 0.05), but not between STR and HIFT. EP was significantly lower in STR compared to END and HIFT (p < 0.01), but not between END and HIFT. The %change in STR during the fatigue test was significantly higher than the change observed in END and HIFT (p < 0.05) but not between END and HIFT, indicating STR were more prone to fatigue than the other groups. The angle at which STR and HIFT recorded their highest peak torque was at 90° of knee flexion, whereas END peaked at 75°. Torque production at all three angles was significantly lower in END compared to STR and HIFT (p < 0.05) but was not significantly different at any angle between STR and HIFT. See table 1 for mean results comparisons.ConclusionTo our knowledge, this study is the first to compare performance related measures in HIFT athletes to traditional strength and endurance specialists. The results indicate that HIFT athletes can exert similar power outputs and absolute strength compared to strength specialists but exhibit a resistance to fatigue that is comparable to endurance specialists.
imageThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.