Author(s): KOJIMA, C., MORISHIMA, T.2, ITO, R.3, YASUNAGA, S.3, SHIMOGAKI, T.3, HASHIMOTO, T.3, ISAKA, T.3, IEMITSU, M.3, Institution: RITSUMEIKAN UNIVERSITY, Country: JAPAN, Abstract-ID: 972

INTRODUCTION:
Tracking changes in blood lactate concentration over time in response to exercise provides us a lot of information regarding anaerobic and aerobic capacities. As such, noninvasive techniques are required to measure lactate concentrations instead of obtaining a small amount of blood invasively. Recently, some previous studies compared blood and salivary lactate concentrations with various exercises, and they indicated that salivary lactate has the potential to be an alternative method to evaluate blood lactate in response to exercises. However, it remains unclear whether salivary lactate reflects changes in blood lactate during post-exercise recovery with or without active rest. Therefore, we investigated blood and salivary lactate concentrations with or without active rest following intensive exercise.
METHODS:
Healthy seven males and four females were recruited (age: 20.6 ± 0.9 years, height: 170.3 ± 8.3 cm, weight: 62.5 ± 7.2 kg). They completed two trials, consisting of control (CON) and active rest (AR) trials. The order of the trials was randomized and the trials were separated with at least a week. In AR trial, participants completed 15 min of light cycling exercise at an individual exercise intensity which was equivalent to 120 bpm of heart rate, whereas in CON trial, participants remained seated for identical period of the AR trial during post-exercise period. In both trial, participants performed 6 sets of 5 min of circuit exercise combined with two resistance exercises for lower extremities and cycling exercise. Blood and salivary concentrations were measured before, immediately after the circuit exercise, immediately after each trial and next morning using a potable devise (Lactate Pro 2, ARKLAY, Inc., Japan). The statistical analysis was performed using a repeated-measured two-way ANOVA. Statistical significance was accepted as a P < 0.05.
RESULTS:
Blood lactate concentrations were significantly increased immediately after circuit exercise in both trial (AR trial: 11.9 ± 2.9 mmol/L, CON trial: 13.4 ± 3.0 mmol/L, Ps < 0.05 vs. before exercise), and a significant difference was observed between trials immediately after each trial (AR trial: 4.2 ± 1.4 mmol/L, CON trial: 6.9 ± 2.8 mmol/L, P < 0.05). Albeit salivary lactate concentrations were also significantly increased immediately after circuit exercise in both trial (AR trial: 4.4 ± 3.0 mmol/L, CON trial: 5.4 ± 3.9 mmol/L, Ps < 0.05 vs. before exercise), the values at completing each trial indicated a significant trend between trials (AR trial: 0.8 ± 0.4 mmol/L, CON trial: 3.1 ± 2.0 mmol/L, P = 0.05). In addition, there was a significant correlation between blood and salivary lactate concentration immediately after each trial (r = 0.856, P < 0.001).
CONCLUSION:
Salivary lactate concentrations may reflect relative changes in blood lactate concentrations during post-exercise period with active rest following intensive exercise.