Effects of Wearing a 50% Lower Jaw Advancement Splint on Biophysical and Perceptual Responses at Low to Severe Running Intensities

Abstract

Acute ergogenic effects of wearing occlusal splints have been reported for aerobic and anaerobic exercises, but the literature centered on performance improvement by using jaw repositioning splints is scarce. We aimed to analyze the effect of wearing a 50% lower jaw advancement splint on biophysical and perceptual responses at low to severe running intensities. Sixteen middle- and long-distance runners performed twice a 7 × 800 m intermittent running protocol (with 1 km‧h−1 increments and 30 s rest periods) in an outdoor track field using two lower intraoral splints (a placebo and a lower jaw advancer). These devices were custom manufactured for each participant and a randomized and repeated measure design was used to compare conditions. No differences between placebo and lower jaw advancer were found (e.g., 52.1 ± 9.9 vs 53.9 ± 10.7 mL·kg−1·min−1 of oxygen uptake, 3.30 ± 0.44 vs 3.29 ± 0.43 m of stride length and 16 ± 3 vs 16 ± 2 Borg scores), but small effects were sometimes observed (e.g., 109.2 ± 22.5 vs 112.7 ± 25.2 L·min−1 of ventilation, ES = −0.42). Therefore, this jaw advancement splint had no substantial ergogenic effect on biophysical and perceptual responses when running at different intensities.

Machine Learning Approach to Model Physical Fatigue during Incremental Exercise among Firefighters

“…The methodology employed for physical exertion monitoring and modelling is summarised in Figure 1 , illustrating the steps followed from the physiological data collection, up to assessing the model’s performance. As described in Figure 2 , volunteers (in light clothing, approximately 0.3 clo [ 26 ]), performed an incremental intermittent running protocol of seven stages of 4 min (with 1 km/h increments and 30 s rest periods in between) on a treadmill (T2100 treadmill; GE, Boston, MA, USA) [ 27 , 28 , 29 ] inside a climatic chamber (FITOCLIMA 25000 EC20; Aralab, Rio de Mouro, Portugal) [ 30 ]. The chamber (3.20 m × 3.20 m), which controls temperature to an accuracy of ± 0.2 °C and relative humidity of ± 5%, was set at thermoneutral conditions (24 °C and 50% of relative humidity).…”

“…The chamber (3.20 m × 3.20 m), which controls temperature to an accuracy of ± 0.2 °C and relative humidity of ± 5%, was set at thermoneutral conditions (24 °C and 50% of relative humidity). The participants’ initial velocity was determined according to their experience and capacity, and validated in a previous bout in which they ran at low intensity at that pre-defined pace [ 28 , 29 ].…”

“…During the experimental protocol, breath-by-breath respiratory gas exchange variables were measured continuously by a telemetric portable gas analyser (COSMED K5; Cosmed, Rome, Italy). It was attached to the participant’s back and placed near their body’s centre of mass to avoid relevant interferences during running [ 28 , 29 ].…”

“…Intraabdominal core temperature was continuously retrieved from low-frequency radio waves transmitted from the gastrointestinal capsules to an external logger (e-Viewer Performance monitor, BodyCAP, France) at 15 s intervals [ 31 ]. The rates of perceived exertion were collected at the end of each 4 min stage through direct feedback from the participants and using the 6–20 Borg scale [ 28 ]. Finally, for complementary information, capillary blood samples for blood lactate analysis were collected (Lactate Pro2; Arkay, Inc., Kyoto, Japan) from the fingertip at baseline, during the 30 s rest stages and at the 1st, 3rd, 5th and 7th min of the recovery stage [ 28 , 29 , 32 ].…”

“…The rates of perceived exertion were collected at the end of each 4 min stage through direct feedback from the participants and using the 6–20 Borg scale [ 28 ]. Finally, for complementary information, capillary blood samples for blood lactate analysis were collected (Lactate Pro2; Arkay, Inc., Kyoto, Japan) from the fingertip at baseline, during the 30 s rest stages and at the 1st, 3rd, 5th and 7th min of the recovery stage [ 28 , 29 , 32 ]. They were included as indicators of the anaerobic system contribution and to validate the physical fatigue levels determined through the Borg scale.…”