Endocrine response to maximum physical effort with superimposed local vibrations

The aim of the presented report was to compare the hormonal responses of cortisol (C) and testosterone (T) during maximum graded aerobic cycling exercise: with vibration (Vib) vs without vibration (noVib). It was directed to sports experts planning the regeneration process or the time/ type of activity during training and competition. Moreover, having clinical implications in the rehabilitation and treatment of injuries, the presented results may be of interest to physiotherapists, as well as ordinary people planning to enrich their physical activity with effective training. Summing up the results, it turns out that adding mechanical vibrations to cycling can potentiate the exercise-induced catabolic state, so deepen some training effects.

• C and T increased in both cycling conditions, that is, in both the Vib and noVib groups.
• The C change was more than 2 times bigger in Vib compared to noVib.
• The size of the change in T did not differ statistically between the groups.
• The vibrations caused a decrease in the T/C ratio which was not observed in the noVib group.

Prepared on the basis of:

Salivary endocrine response following a maximal incremental cycling protocol with local vibration. Jemni M, Marina M, Delextrat A, Tanner A et al. (2020) PLoS ONE 15(9):e0238051.

Study population

Twelve active men (25 ± 5 years; 181 ± 5 cm; 80.7 ± 11.1 kg).

Test procedure

Each participant performed two maximum incremental exercise tests on the stationary bike PowerBIKE (Power Plate, The Netherlands), one with local vibration (Vib) and the other without vibration (noVib), in random order on separate days. The tests were conducted at the same time of day (09:00), with a recovery period of 72 hours between the first and the second. The protocol consisted of 3-minute incremental steps performed on the bike. Gas exchange and heart rate were continuously assessed and blood lactate was recorded at the end of each incremental stage. Saliva samples were taken before and immediately after the test and analyzed for C and T.

Results

The results show that C and T increased under both cycling conditions. The magnitude of the change in C was significantly higher in Vib (83%) compared to noVib (approx. 30%; p = 0.014). The size of the change in T did not differ statistically between the groups (p = 0.715). The vibrations caused a decrease in the T/C ratio (p = 0.046), but no significant changes were observed in noVib (p = 0.476).

Comment

The main goal was to investigate the endocrine response (based on saliva samples) to cycling exercise with simultaneously administered vibrations, compared to cycling without vibrations. Cycling, both in the Vib or noVib group, caused an increase in cortisol levels, but dramatically higher in the Vib group. Testosterone increased in both groups with no statistically significant differences between them. Vibration thus induced a significant decrease in the T/C ratio, while no significant changes in the T/C ratio were observed in noVib.

The present study suggests that the addition of mechanical vibration to cycling may potentiate the catabolic effort of cycling.

Sports experts, especially cyclists, should review these results in order to carefully plan the recovery process and activity during training and competition. In addition, the obtained results may have potential clinical implications for the elderly and people undergoing rehabilitation after illness and injury.

In this context, future research should therefore also analyze the long-term response to exercise with the addition of local mechanical vibrations.

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