Quantification of the Metabolic and Physical Demands of the 90-Second Box Jump

Quantification of the Metabolic and Physical Demands of the 90-Second Box Jump

The goal of the 90-second box jump (BJ90) is to perform as many lateral jumps as possible onto and off of a bench within 90 seconds. We aimed to determine the physiological and biomechanical demands of the BJ90. Sixteen trained males (age range 23–45 y) performed a cycling test to determine maximal oxygen uptake (VO2 max), three countermovement jumps (CMJ) to determine explosive leg strength and the BJ90 on 1–3 occasions. Heart rate (HR), VO2, and ground reaction forces were recorded throughout the BJ90. Acceleration, work and power were derived from force measurements. Blood lactate and oxygen debt were measured after the test and aerobic energy contribution was estimated. Subjects performed (mean ± SD (range)) 75 ± 13 (52-94) jumps. Total work was 64.0 ± 6.3 (53–78) kJ, denoting a work rate of 711 ± 70 (590–868) W. Mean acceleration and impulse for the ground contact phase were 14.9 ± 4.3 (7.5–22.3) m/s2 and 521 ± 94 (410–783) N·s, respectively. Maximal concentric power remained higher than in CMJ for the first 60 s but dropped over the last 30 s to values similar to CMJ. Average concentric power was always lower than in CMJ, and dropped continuously throughout the BJ90. Maximal eccentric power was of lesser magnitude than in CMJ. Peak VO2 and HR were 93.1 ± 8.3% (77–110) and 95.6 ± 2.6% (89- 102) of maxima, respectively. Metabolic intensity corresponded to 136 ± 12 (108–156)%VO2 max (80.1 ± 6.3 ml/min/kg) and aerobic contribution to total energy was 55.9 ± 4.2%. Metabolic efficiency was 34.5 ± 3.6%. Blood lactate reached 13.4 ± 1.6 (9.0-17.0) mM. Conclusions: Physiologically speaking, the BJ90 is similar to giant slalom skiing, whereas the movement frequency corresponds to slalom racing. The faster rate of force development in the BJ90 represents the main difference from ski racing.