Relationship between infrared thermography and muscle damage markers in physically active men after plyometric exercise.

Plyometric training has been used in several sports and fitness programs to improve jumping ability and explosive strength, both in individual and team sports. Eccentric muscle actions, such as those performed during plyometric jumps, induce muscle damage and consequently a rise in skin temperature (Tsk). Thus, the purpose of this study is to assess the response of infrared thermography measurement as an indirect marker of muscle damage after a protocol of plyometric jumps in physically active subjects. Therefore, for the aim of this study ten male subjects with no previous experience in plyometric training participated in the research (age 22.5 ± 3.3 years, weight 71.7 ± 11.0 kg, height 171.1 ± 5.3 cm, and fat mass 15.5 ± 4.7%). To assess the muscle damage, countermovement jump (CMJ), creatine kinase (CK), delayed-onset muscle soreness (DOMS) and infrared thermography (IRT) were measured at 24, 48, and 72 h after plyometric exercise. The acute exercise protocol of plyometric jumps induced muscle damage, as shown by the CK and DOMS (24 and 48 h, p < 0.05) but no statistical difference was shown between the moments analyzed in Tsk (warm zone). Nevertheless, when comparing baseline to 48h, a moderate effect was found in the Tsk (warm zone) for anterior right thigh (ES = 1.1) and posterior left thigh (ES = 0.9) and large effect was found for anterior left thigh (ES = 1.4) and posterior right thigh (ES = 1.3). A moderate effect in the Tsk (warm zone) was found for posterior right and left thigh (ES = 0.9 and ES = 1.1, respectively) when comparing baseline to 72h of IRT. These results suggest that a plyometric jumping session alters CK and DOMS, as well as the thigh's skin temperature in an evident way, bringing up a possible relation with markers of muscle damage.

Thermoregulatory and metabolic responses to a half-marathon run in hot, humid conditions.

This study describes the thermoregulatory and metabolic responses during a simulated half-marathon (21 km) run performed outdoors in a hot, humid environment. Ten male runners were recruited for the study, The run was carried out individually under solar radiation on a predetermined path in the following environmental conditions (ambient temperature: 27.96 ± 1.70 °C, globe temperature: 28.52 ± 2.51 °C, relative humidity: 76.88 ± 7.49%, wet bulb globe temperature: 25.80 ± 1.18 °C). Core temperature, skin temperature, head temperature, heat storage, heart rate, expired gases, rating of perceived exertion, and speed were measured or calculated before the start, every 3 km, and immediately following the run. Comparisons were made for each dependent variable using one-way repeated measures analysis of variance tests, and a Bonferroni test. Average run time and pace were 101:00 ± 9:52 min and 4:48 ± 00:16 min km-1, respectively. Participants significantly reduced their running speed, oxygen consumption, and heat storage at 9 km (p < 0.05). While core temperature was significantly increased at 6 km (p < 0.05) before plateauing for the remainder of the run. The key finding was that most of the runners reduced their pace when a Tcore of 39 °C was reached which occurred between 6 and 9 km of the run, yet runners were able to increase their speed demonstrating an "end-spurt" near the end of the run.