Effects of Individualized Low-Intensity Exercise and Its Duration on Recovery Ability in Adults

Abstract

Exercise is recommended to increase physical health and performance. However, it is unclear how low-intensity exercise (LIE) of different durations may affect or improve recovery ability. This study aimed to investigate how LIE-duration with the same volume affects recovery ability in adults. Twenty healthy male adults participated in this study. Participants were randomly assigned to the 30-min (n = 10) or the 1-h LIE group (n = 10). The intervention included sixteen exercise sessions/four weeks with a 30-min LIE group, and eight exercise sessions/four weeks with a 1-h LIE group. Heart rate (HR) corresponding to <2 mmol∙L−1 blood lactate (La−) was controlled for LIE. Pre- and post-testing was conducted before and after 4-week LIE and tests included jogging/running speed (S), HR, and differences (delta; ∆) in HR and S between pre- and post-testing at 1.5, 2.0, and 4.0 mmol∙L−1 La−. Only the HR at 2.0 mmol∙L−1 La− of the 30-min LIE group was decreased in the post-test compared to the pre-test (p = 0.043). The jogging/running speed of the 1-h LIE group was improved in the post-test compared to the pre-test (p < 0.001, p = 0.006, p = 0.002, respectively). ∆HR at 2.0 and ∆S between the 30-min and 1-h LIE group at 1.5, 2.0, and 4.0 mmol∙L−1 La− were significantly different (p = 0.023, p < 0.001, p = 0.002, and p = 0.019, respectively). Furthermore, moderate to high positive correlations between ∆HR and ∆S of all subjects at 1.5 (r = 0.77), 2.0 (r = 0.77), and 4.0 (r = 0.64) mmol∙L−1 La− were observed. The 1-h LIE group showed improved endurance not only in the low-intensity exercise domain, but also in the beginning of the moderate to high-intensity exercise domain while the 30-min LIE group was not affected by the 4-week LIE intervention. Therefore, LIE (<2.0 mmol∙L−1) for at least 1-h, twice a week, for 4 weeks is suggested to improve recovery ability in adults.

The ability of energy recovery in professional soccer players is increased by individualized low-intensity exercise

“…HIIE such as repeated sprints with the ball requires increased phosphagen and glycolytic metabolism [ 14 ]. However, ATP is resynthesized rapidly from phosphocreatine (PCr) during LIE and the accumulated lactate via substrate-level and oxidative phosphorylation delays HIIE during the second half [ 5 , 10 , 11 , 15 , 16 ].…”

“…In this regard, lactate threshold (LT) tests have been used by sports scientists for more than fifty years to measure individualized exercise prescriptions for elite athletes. Furthermore, the blood lactate concentration under different exercise intensities is a sensitive biomarker of endurance than maximal oxygen uptake (VO 2max ) [ 10 , 11 , 17 – 21 ]. The improved recovery ability and general endurance are interpreted by the rightward shift of the exponential lactate curve in the LT test [ 10 , 11 , 17 , 18 , 22 ].…”

“…Furthermore, the blood lactate concentration under different exercise intensities is a sensitive biomarker of endurance than maximal oxygen uptake (VO 2max ) [ 10 , 11 , 17 – 21 ]. The improved recovery ability and general endurance are interpreted by the rightward shift of the exponential lactate curve in the LT test [ 10 , 11 , 17 , 18 , 22 ]. The blood lactate level in the LT test is used to measure different exercise intensities including zones 1 (low), 2 (threshold/moderate), and 3 (high) [ 10 , 11 , 23 – 25 ].…”

“…The improved recovery ability and general endurance are interpreted by the rightward shift of the exponential lactate curve in the LT test [ 10 , 11 , 17 , 18 , 22 ]. The blood lactate level in the LT test is used to measure different exercise intensities including zones 1 (low), 2 (threshold/moderate), and 3 (high) [ 10 , 11 , 23 – 25 ]. LIE at lactate levels < 2 mmol∙L −1 (zone 1) is separated into recovery and extensive exercises.…”

“…LIE at lactate levels < 2 mmol∙L −1 (zone 1) is separated into recovery and extensive exercises. The recovery and extensive exercises are defined before and until the first onset of the lactate curve (LT 1) [ 10 , 11 , 23 , 26 ]. Most training volumes include predominantly zone 1 exercise intensities (≥ 87%) involving middle- and long-distance running such as marathons to improve athletes’ endurance [ 27 ].…”