# Changing the Mandibular Position in Rowing: A Brief Report of a World-Class Rower

## TL;DR

A world-class rower showed improved performance and reduced muscle effort when using a mouth splint to adjust jaw position during rowing.

## Contribution

This study demonstrates that mandibular repositioning via an intraoral splint can enhance rowing economy and reduce upper body muscle activation.

## Key findings

- Oxygen uptake was lower with the splint at higher exercise intensities.
- Rowing technique changed with the splint, including slower frequency and longer propulsive movement.
- The splint reduced upper body muscle activation while increasing lower body activity and rowing economy.

## Abstract

We investigated the acute biophysical responses of changing the mandibular position during a rowing incremental protocol. A World-class 37-year-old male rower performed two 7 × 3 min ergometer rowing trials, once with no intraoral splint (control) and the other with a mandibular forward repositioning splint (splint condition). Ventilatory, kinematics and body electromyography were evaluated and compared between trials (paired samples t-test, p ≤ 0.05). Under the splint condition, oxygen uptake was lower, particularly at higher exercise intensities (67.3 ± 2.3 vs. 70.9 ± 1.5 mL·kg−1·min−1), and ventilation increased during specific rowing protocol steps (1st–4th and 6th). Wearing the splint condition led to changes in rowing technique, including a slower rowing frequency ([18–30] vs. [19–32] cycles·min−1) and a longer propulsive movement ([1.58–1.52] vs. [1.56–1.50] m) than the control condition. The splint condition also had a faster propulsive phase and a prolonged recovery period than the control condition. The splint reduced peak and mean upper body muscle activation, contrasting with an increase in lower body muscle activity, and generated an energetic benefit by reducing exercise cost and increasing rowing economy compared to the control condition. Changing the mandibular position benefited a World-class rower, supporting the potential of wearing an intraoral splint in high-level sports, particularly in rowing.