Acute arterial stiffness, testosterone and force production responses and recovery from different combined strength and endurance loading models

Abstract

Much of the differences between strength (S) and endurance (E) exercise can be attributed to the contrasting endocrinological and molecular responses between the two exercise modes. From the current literature, it seems that aortic arterial stiffness, a reliable cardiovascular mortality predictor, also responds differently

to these two modes of exercise. It is thus important to understand the acute responses that combined exercise loads may invoke, as acute responses are known to drive chronic adaptations. Furthermore, testosterone has been cited as a key hormone in cardiovascular protection and its effects may mediate blood flow and hemodynamics. Currently, there

are very few studies investigating

combined exercise loadings and its effect on central hemodynamic

and endocrine response. Therefore, the purpose of the study was to determine the acute arterial stiffness and testosterone response to different concurrent strength and endurance models of exercises. In addition, the recovery profile from these loadings will also be elucidated to gain a better understanding of its time course. A group of eight male (33.5 ± 5.9 years) recreationally endurance trained participants took part in the study. All participants took part in three loading sessions; one with S loading followed immediately by E loading (S+E), vice versa (E+S), and integrated (INT), where E and S alternated

during the session. Participants were tested for their E (maximal oxygen consumption; VO 2MAX ) and S performance (maximal bilateral dynamic leg press, 1RM) and performed all loadings in a randomized order. S primarily focused on leg extensor muscles including both maximal and explosive exercises (2 x 10 reps squat jumps, drop jumps, bounding and 3 x 10 reps leg press with 80% of 1 RM with 2min rest between the sets) and E was performed as continuous running with intensity between 80 – 85% VO 2MAX . Pulse wave velocity (PWV) and blood pressure

values were determined pre (PRE), post (POST) and 30 minutes after (POST30). Serum testosterone concentrations, maximum voluntary contraction (MVC) and rapid force production (RFP) were determined for PRE and POST loadings and repeated after recovery of 24h and 48h. The main findings were significant decreases in mean PWV PRE to POST (7.9 ± 0.7 m/s vs 7.3 ± 0.8 m/s, respectively) (p = 0.017) for combined exercise loadings and mean SBP POST to POST30min (128.0 ± 5.1 vs 134.6 ± 5.9 mmHg, respectively) (p = 0.032). Mean DBP had a statistically

significant interaction effect between time and loading (F(4, 28) = 3.677, p = 0.016). There was a statistically significant reduction in MVC from PRE to POST (3291 ± 1007 N vs 2888 ± 804 N) (p = 0.037), as well as in RFP from PRE to POST (2182 ± 294 vs 1917 ± 239 N) (p = 0.005). In summary, the present results showed that an order effect may exist, when SBP and DBP are taken together into consideration with PWV. Combined exercise did not lead to detrimental effects in PWV and the ES order had the larger response. Additionally, INT showed the least amount of force production deficit among all three orders. These findings may be useful in assisting the exercise prescription in elderly, hypertensive and pre-hypertensive populations.