ACCELERATION TRANSMITTED TO THE HUMAN BODY DURING CYCLING: EFFECT OF A ROAD BIKE DAMPING SYSTEM

The objective of this study was to examine the influence of a road bike damping system on accelerations transmitted to the cyclist. Thirty male subjects performed trials with and without vibration on a damped and non-damped road racing bike at three different power level. Three-dimensional accelerations at thigh, shank, lower back, acromion, neck and forearm were recorded to quantify the athlete-bike interaction. Vibrations were found to effect the entire body significantly. Significant differences regarding the damped and non-damped bike were observed for the vibrations transmitted to the upper body, while lower extremity loading was comparable. Therefore road bike damping reduces mechanical load at the upper extremities and torso effectively and thereby possibly contributes to comfort and injury prevention. This might provide beneficial information to coaches and athletes for material selection

UPPER BODY VIBRATION TRANSMISSION IN CYCLING

This study aimed to identify the effects of vibration frequency on upper body transmissibility in cycling. We hypothesized, that vibrations around 15 Hz are transmitted more intensely to the upper body than vibrations around 45 Hz. The effect of the independent variable vibration frequency on the dependent variable vibration transfer ratio of the torso and the hand-arm system was analysed. Nineteen amateur cyclists (75.1 ± 5.7 kg, 1.78 ± 0.05 m) performed test rides on a racing bike which was mounted on two vibration plates. During the vibration interventions VIB LOW (Front-/ Rear dropout: 17 Hz / 12 Hz), VIB MED (Front-/ Rear dropout: 32 Hz / 27 Hz) and VIB HIGH (Front-/ Rear dropout: 47 Hz / 42 Hz) accelerations at the lower back, neck, hand and acromion were recorded with 3D sensitive accelerometers. Transfer ratios occurred in between 1.82 ± 0.51 from the lower back to the neck for VIB LOW and 0.06 ± 0.03 from the hand to the shoulder for VIB HIGH. The lower back – neck and hand - shoulder transfer ratios decreased from VIB LOW to MED to HIGH significantly, which supports our initial hypothesis. These results suggest that vibrations around/below 15 Hz contribute substantially to upper body vibration exposure in cycling

ROAD BIKE DAMPING: COMFORT OR PERFORMANCE RELATED?

The aim of this study was to determine if a road bike specific damping system increases short term performance. Muscular activation of the triceps surae and quadriceps femoris, oxygen consumption, heartrate and maximum power output of thirty male, trained cyclists were recorded. The participants performed on a damped and non-damped road racing bike six-minute steady state and four-minute all-out tests with and without vibration. Vibration significantly increased the mean activation of the triceps surae and significantly increased oxygen uptake and heartrate. Damping had no impact on muscular activation, energy requirements and cardiopulmonary response. It is therefore concluded, that cycling specific vibration affects the musculoskeletal system and slightly increases total energy demand. Damping contributes to upper body comfort but does not influence short term performance directly

ROAD TO LAB: COBBLESTONE CYCLING VIBRATIONS TRANSFERRED TO THE LAB

The purpose of the study was to provide vibration recommendations for laboratory-based cycling interventions derived from field tests on cobblestones. For that purpose, the vertical accelerations of the front and rear dropouts (points of wheel fixation at the frame) of the bike frame were recorded, with five experienced cyclists riding on cobblestones at different velocities. Lab vibration recommendations are based on the median frequency (34.6 ± 1.2 – 45.6 ± 0.5 Hz), rms of acceleration (5.5 ± 0.3 - 10.2 ± 0.6 g) , peak acceleration (48.5 ± 3.8 g) , mean amplitude (3.6 ± 4.3 – 5.0 ± 6.4 mm) and peak amplitude (69.7 ± 23.4 mm) of the dropouts. For a lab-based approach with vibration plates, the vibration stimulus should be applied (I) to the rear and front dropout, (II) with two different frequencies used for front (36 - 46 Hz) and rear (32 - 39 Hz) (III) and a mean vertical amplitude of 4 mm. The parameters presented provide the basis for vibration-related material testing, motion analysis or physiological performance testing in cycling

GRAVEL BIKE VIBRATIONS

TThe purpose of this pilot study was to explore the vibration exposure of Gravel bikes at different tire pressures. Therefore, 9 cyclists (73.7 ± 10.2 kg, 1.78 ± 0.06 m) rode a 150 m flat gravel section at a constant speed of 25 km/h with three tire pressure conditions (1.5, 2.5, 3.5 bar). Horizontal and vertical accelerations at the front dropout (FDO) and rear dropout (RDO) were recorded. Reducing the tire pressure from 3.5 to 1.5 bar resulted in a significant decrease in the resulting acceleration at the FDO from 3.41 ± 0.18 g to 2.07 ± 0.07 g and at the RDO from 2.78 ± 0.14 g to 1.56 ± 0.07 g. When comparing the ratio of horizontal and vertical rms of acceleration, ratios of up to 0.9 for the FDO and up to 0.47 for the RDO were found. This indicates that horizontal accelerations, especially at the FDO contribute considerably to the overall vibration exposure of the bike. The two main conclusions are that (I) damping systems in gravel bikes should take into account not only vertical but also horizontal accelerations and (II) tire pressure adjustment has a similar potential for vibration management on gravel as more complex damping systems

ANALYZING SELF-ASSESSMENT OF PUNCHING INTENSITY BETWEEN EXPERIENCED AND INEXPERIENCED BOXING ATHELETES

Due to the direct confrontation with a training or sparring partner, boxing and other martial arts represent a unique situation and the importance of accurate self-assessment, in which an incorrect self-assessment can lead to severe injuries for the participant himself or the sparring partner. The study aimed to investigate the self-assessment accuracy and repeatability between 26 experienced and inexperienced athletes for pre-defined punching intensities using a developed boxing monitoring sensor system. The results show considerable overestimated self-assessed punching intensities in the inexperienced in contrast to the experienced group revealing a substantial deficiency of punching intensity self-assessment

A METHODOLOGICAL APPROACH FOR SIMULATING MUSCULOSKELETAL LOADING IN THE HEAD AND NECK REGION FOLLOWING BOXING PUNCHES TO THE HEAD

The aim of various combat sports is to win the competition by throwing repetitive punches predominantly to the opponent\u27s head. These hitting blows can lead to short and potentially long-term adverse health consequences. The aim of the current study is to introduce an approach that estimates 3D punch forces acting on a struck subject\u27s head. The procedure refers to marker-based kinematic measures and subsequently implementing them into a musculoskeletal head-neck model in OpenSim. The results showed reasonable effective mass estimates, whereby the relatively small force magnitudes and the activation of the reserve moments require methodological modifications followed by the validation of the proposed approach

REDUCED MOVEMENT ADAPTABILITY IN SIDESTEPPING – A POSSIBLE SOURCE OF INJURY RISK

Adapting to different task constraints provides insight into how malleable an athlete’s movement dynamics are. The purpose of this pilot study was to investigate whether athletes can adequately change their preferred movement strategy during sidestepping when exposed to a manipulation task. Reduced movement adaptability was hypothesized to be one risk factor for ACL injuries. Fourteen male team sport athletes were investigated. The response to the manipulation task was intra-individual, with rearfoot strikers being less able to adapt their movement strategy and the resulting movement was even higher associated with ACL risk factors. Forefoot strikers were able to adapt their movement. This suggests, that athletes need to be investigated individually as group-based analyses might cover effects and that movement adaptability should be considered when evaluating injury risk

CHANGES IN EMG SIGNALS WHILE RUNNING ON DIFFERENT SURFACES

The purpose of this study was to quantify changes in EMG signals while running on different surface conditions. Volunteers (n = 47) participated in a study, where surface EMG was recorded from six muscles of the lower extremity while running on three different surfaces (barefoot on grass, barefoot on tartan, shod on tartan). Different surface conditions led to changes in muscle activation within all subjects. Muscle activation patterns were highly individual and different for men and women. Changes of activity patterns depending on running surface were muscle specific and clearly different between gender groups. A deeper understanding of muscular activation while running may yield valuable information for future footwear design and injury sources