Propulsive force is a determinant of swimming performance. Several methods have been proposed to estimate the propulsive force in human swimming; however, their practical use in coaching is limited. Herein, we propose a novel method for estimating the propulsive force generated by swimmers’ hands using an inertial measurement unit (IMU) and pressure sensors. In Experiment 1, we use a hand model to examine the effect of a hand-mounted IMU on pressure around the hand model at several flow velocities and water flow directions. In Experiment 2, we compare the propulsive force estimated using the IMU and pressure sensors ($F_{\mathrm{IMU}}$) via an underwater motion-capture system and pressure sensors ($F_{\mathrm{Mocap}}$). Five swimmers had markers, pressure sensors, and IMUs attached to their hands and performed front crawl swimming for 25 m twice at each of nine different swimming speeds. The results show that the hand-mounted IMU affects the resultant force; however, the effect of the hand-mounted IMU varies with the flow direction. The mean values of $F_{\mathrm{Mocap}}$ and $F_{\mathrm{IMU}}$ are similar (19.59 ± 7.66 N and 19.36 ± 7.86 N, respectively; intraclass correlation coefficient_(2,1) = 0.966), and their waveforms are similar (coefficient of multiple correlation = 0.99). These results indicate that the IMU can estimate the same level of propulsive force as an underwater motion-capture system.

The purpose of this study was to elucidate pelvic orientation angles using a single lower back-mounted inertial sensor during sprinting. A single inertial sensor was attached to each sprinter’s lower back, used to measure continuous pelvic movements including pelvic obliquity (roll), anterior-posterior tilt (pitch) and rotation (yaw) during sprinting from a straight to bend section. The pelvic orientation angles were estimated with the three-dimensional sensor orientation using a sensor fusion algorithm. Absolute angles derived from the sensor were compared with angles obtained from an optical motion capture system over a 15 m length. The root mean squared error between the sensor and motion capture data were 4.1° for roll, 2.8° for pitch and 3.6° for yaw. Therefore, the sensor was comparable to the motion capture system for tracking pelvic angle changes. The inertial sensor is now supported as a valid tool to measure movements of the pelvis during sprinting.

The transition from a stationary crouch on running-blocks to an erect running position is critical to success in sprint running. Three elite sprinters repeated five sprint starts on a 50 m-long instrumented running track each wearing three inertial measurement units (IMU) on both shanks. The IMU profiles and force plate data was highly consistent between runs. The increasing maximum ground force was correlated with the IMU data using a linear fit and gyroscope triggered acceleration component. Both techniques show promise (r² > 0.5). This is of significant interest to athletes and coaches using IMUs rather than a long, instrumented running track.

With the increasing rise of professionalism in sport, athletes, teams, and coaches are looking to technology to monitor performance in both games and training in order to find a competitive advantage. The use of inertial sensors has been proposed as a cost effective and adaptable measurement device for monitoring wheelchair kinematics; however, the outcomes are dependent on the reliability of the processing algorithms. Though there are a variety of algorithms that have been proposed to monitor wheelchair propulsion in court sports, they all have limitations. Through experimental testing, we have shown the Attitude and Heading Reference System (AHRS)-based algorithm to be a suitable and reliable candidate algorithm for estimating velocity, distance, and approximating trajectory. The proposed algorithm is computationally inexpensive, agnostic of wheel camber, not sensitive to sensor placement, and can be embedded for real-time implementations. The research is conducted under Griffith University Ethics (GU Ref No: 2016/294).

This study elucidated kinetic and kinematic changes between control and weighted vest sprinting with a load of 7% body mass. Fourteen male sprinters completed 60 m control and vest sprints over a long force platform system. Step-to-step ground reaction force and spatiotemporal variables were grouped, representing the initial acceleration (1st-4th steps), middle acceleration (5th-14th steps), later acceleration (15th step-step before maximum velocity reached) and maximum velocity (stride where maximum velocity reached) phase during each trial. Two-way ANOVA with post hoc Tukey HSD and a Cohen's d effect size with 95% confidence intervals elucidated the difference between trials and phases. Between control and vest trials the velocity decreased (3.41-3.78%) through trivial-small step length (1.95-2.72%) and frequency (0.87-1.54%) decreases. Vertical impulse increased (6.46-6.78%) through moderate support time increases (4.84-6.00%), coupled with no effective vertical mean force differences during the vest trial, compared to the control. There was no significant interaction between trials and phases. Therefore, although weighted vest trials did not increase vertical mean force production, vests did induce an increased vertical force application duration during the support phase step-to-step while supporting a larger total load (body mass plus vest mass).

Multiple-hop tests are commonly used in both performance and rehabilitation settings to assess neuromuscular function. This study aimed to explore the relationship between hop performance and sprint ability. Specifically, it focused on three goals: (1) examining the connection between 3-Hop and 5-Hop distances and sprint performance and comparing the strength of relationship between hop kinetics and sprint times; (2) investigating two methods of calculating the 3-Hop and 5-Hop Reactive Strength Indexes (RSI_hors) and their relationship to sprinting; and (3) assessing whether hop ratios or kinetic variables could distinguish sprinters of varying abilities. Forty-four male sportsmen participated, completing 3-Hop and 5-Hop tests and sprint times (5–45 m) over 54 inground force platforms. Ground reaction forces (GRFs) were collected during hop trials and horizontal and vertical hop propulsive and braking kinetics were determined. Results showed strong negative correlations between hop distances and sprint times (r = −0.700 to −0.796), while kinetic variables showed weaker relationships with sprint performance (r = −0.554 to 0.017). RSI_hor, derived from hop distance, correlated more strongly with sprint performance than RSI_hor from flight time. Hop ratios (5-Hop/3-Hop) did not differentiate fast from slow sprinters, and maximal vertical force and horizontal propulsive impulse were the best predictors of 10 m and 40 m sprint times. These findings suggest that hop distance and RSI_hor are valuable tools for assessing sprint performance and reactive strength.