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Featured Application: This training regimen can be used as a time-efficient protocol for people with lower levels of aerobic fitness to kickstart their fitness journey. The training loads applied can be used as initial mesocycle loads for untrained participants, noting that, through effective periodization, the HITT intensities will periodically increase to provide an ongoing adaptive stimulus. Further, for aerobically trained individuals (>40 mL/kg/min), we suggest that this program be modified by increasing the prescribed training intensities to induce a sufficient stimulus to increase their baseline strength and aerobic parameters. An alternative use of this intervention is as a short (off-/pre-season) training regimen within sports clubs to boost strength and endurance parameters through a brief, but intense, time-efficient training approach. Finally, the described intervention could be implemented in occupational settings (e.g., fly-in–fly-out work camp labour workers in mines), where the benefit from incorporating a systematic training regimen, especially when the time devoted to exercise is limited, can lead to general health benefits. There is conflicting evidence on whether concurrent aerobic endurance and resistance training (RT) leads to synergistic enhancements in aerobic capacity and muscular strength or causes interference, limiting performance gains. We developed a concurrent training (CT) intervention, including full-body dynamic RT combined with high-intensity interval training (HIIT), on a cycle ergometer to determine whether a brief CT intervention is beneficial to both muscular strength and aerobic capacity. In an exploratory pilot study, participants (n = 10; male = 4) undertook a four-week CT intervention consisting of RT, including six compound movements (bench press, squat, deadlift, Pendley row, squat jumps, and rack pulls), plus cycle HIIT. The pre-/post-intervention improvements were assessed via bench press and leg press 3RM testing, an isometric mid-thigh pull, a countermovement jump, and the change in the relative V ˙ O2max. We observed significant (p < 0.1) increases in the bench press (6.4%), leg press (6.7%), IMTP (11.1%), and relative V ˙ O2max (7%) results. Interestingly, the participants with the highest pre-intervention relative V ˙ O2max demonstrated no performance improvements. These pilot test results suggest that CT is an effective strategy that enables synergistic enhancements that can be observed with very low training volumes. This suggests that CT is an effective strategy for improving muscular strength and aerobic endurance in non-elite physically active individuals. [ABSTRACT FROM AUTHOR]

The objective of this research was to validate a single, trunk-mounted wearable sensor (Optimeye S5, Catapult Australia, Melbourne) to measure the cadence of swimming strokes, cycling pedals and running strides in a triathlon. While similar validations have been performed in swimming and running, it is a novel application in cycling, and thus, across a whole triathlon. Seven triathletes were recruited to participate in a sprint distance triathlon which was filmed and simultaneously measured by a single, trunk-mounted wearable sensor. To validate the wearable sensor, individual swimming strokes, cycling pedal strokes and running strides were manually counted by viewing the wearable sensor data and video footage. While analysing cycling data, changes in cycling subtask performances were noticed, thus, a secondary analysis in cycling was conducted to investigate. The 95% limits of agreement analysis indicated the sensor validly measured swimming strokes (mean bias = −0.034 strokes), cycling pedal strokes (mean bias = −0.09 strokes) and running strides (mean bias = 0.00 strides) with minimal to no bias (p > 0.05). Further analysis of cycling revealed the wearable sensor is an acceptably valid tool to measure the duration of out of saddle riding (mean bias = 0.08 s), however, significant differences in the duration of in saddle riding (mean bias = −0.5 s) and coasting were identified (mean bias = 0.39 s). A single trunk mounted wearable sensor is a valid tool to measure movement cadence in a triathlon, however, further validation is required to generate a full understanding of cycling subtask performances. [ABSTRACT FROM AUTHOR]

Featured Application: Improving cornering skill has the potential to improve overall cycling performance. However, clinically used balance tests do not reflect cornering performance. More cycling-specific balance tests need to be developed to better assess cycling performance. Balance is paramount to safe and successful cycling, both in competition and recreation. Balance has been investigated in the return-to-cycling context, but its relationship to cycling performance is unknown. Our study aimed to analyse the relationship between balance, measured by common clinical balance tests, and cycling performance. Seven competitive cyclists participated in this cross-sectional correlational study. We collected field-based measures of cycling performance, including mean velocity, minimum and maximum velocity, mean corner speed, average lap time, and lean angle. Also, we measured balance via the balance error scoring system, the star excursion balance test, the lateral reach test, and the modified Bass test of dynamic balance. Strong correlations between cornering performance and cycling performance (r = 0.65–0.87, p < 0.01) were detected. Weak correlations between clinical balance tests and cycling performance (r = 0.33–0.53, p < 0.05) were observed. In conclusion, our study showed that improving cornering performance has the potential to improve overall cycling performance. We also found no clear correlations between our clinical balance tests and cycling performance. These weak correlations between postural control in standing and cycling performance suggest that standing balance and balancing during cycling are distinct motor control processes. [ABSTRACT FROM AUTHOR]

Australian aerial skiers are recruited from other acrobatic sports through a nationally coordinated transition program. However, there is limited understanding of how to train transferring athletes for both optimal performance and injury prevention. The aim of this study was to test whether an athletic profile could be used to identify which skills that gymnasts possess are more and less likely to transfer to aerial skiing based on similarities and differences in the athletes' physical attributes. Six elite female aerial skiers and five state- and national-level female gymnasts completed a test protocol involving drop-landing, countermovement jump, isokinetic strength of the knee flexors and extensors, flexibility and anthropometrical profile. Aerial skiers and gymnasts had an anthropometrical profile ideal for acrobatic efficiency, but gymnasts had smaller thigh girth and greater knee range of motion. These results suggest that gymnasts are more likely to succeed in transferring to aerial skiing's acrobatic skills than skiing and landing skills. We suggest that gymnasts transferring to aerial skiing undertake pretransfer training designed to improve hamstring isometric strength and dynamic stability of the knee to reduce the risk of knee injury and improve their ability to maintain a crouched position. [ABSTRACT FROM AUTHOR]

EMG-driven musculoskeletal modeling is a method in which loading on the active and passive structures of the cervical spine may be investigated. A model of the cervical spine exists; however, it has yet to be criterion validated. Furthermore, neck muscle morphometry in this model was derived from elderly cadavers, threatening model validity. Therefore, the overall aim of this study was to modify and criterion validate this preexisting graphically based musculoskeletal model of the cervical spine. Five male subjects with no neck pain participated in this study. The study consisted of three parts. First, subject-specific neck muscle morphometry data were derived by using magnetic resonance imaging. Second, EMG drive for the model was generated from both surface (Drive 1: N = 5) and surface and deep muscles (Drive 2: N=3). Finally, to criterion validate the modified model, net moments predicted by the model were compared against net moments measured by an isokinetic dynamometer in both maximal and submaximal isometric contractions with the head in the neutral posture, 20 deg of flexion, and 35 deg of extension. Neck muscle physiological cross sectional area values were greater in this study when compared to previously reported data. Predictions of neck torque by the model were better in flexion (18.2% coefficient of variation (CV)) when compared to extension (28.5% CV) and using indwelling EMG did not enhance model predictions. There were, however, large variations in predictions when all the contractions were compared. It is our belief that further work needs to be done to improve the validity of the modified EMG-driven neck model examined in this study. A number of factors could potentially improve the model with the most promising probably being optimizing various modeling parameters by using methods established by previous researchers investigating other joints of the body. Keywords: cervical spine, musculoskeletal modeling, neck, validity

The purpose of this study was to compare surface electromyography (EMG) activation levels of selected neck muscles for two common neck-training modalities (Thera-Band and Cybex). Seventeen asymptomatic subjects (eight men and nine women) with a mean age 23.4 years were recruited. EMG activation normalized to maximal voluntary isometric contraction (MVIC) was measured with subjects performing exercises with green, blue, and black Thera-Bands and 50%, 70%, and 90o/0 of 3RM for the Cybex modality. Four variables were used to depict exercise intensity: average and peak EMG activation in the concentric and eccentric phases. Significant differences (P [less than or equal to] 0.05) in EMG activation were evident when comparing intensities of the Cybex modality with each other and when comparing the Cybex intensities with Thera-Band intensities in most cases. Minimal differences were found among differing intensities of Thera-Band. Thera-Band exercise resulted in low-level EMG activation (range, flexion 3.8-15.7% MVIC; range, extension 20.2-34.8% MVIC); therefore, such exercise may be useful in rehabilitation programs. Cybex exercise (range, flexion 20.9-83.5% MVIC; range, extension 40.6-95.8% MVIC) may be useful for occupation-related injury prevention. However, exercise prescription should be undertaken with care as the mechanical loading on passive spinal structures is unknown. KEY WORDS Them-Band, Cybex, strength, rehabilitation, intensity

Optimal tuning of leg stiffness has been associated with better running economy. Running with a load is energetically expensive, which could have a significant impact on athletic performance where backpack carriage is involved. The purpose of this study was to investigate the impact of load magnitude and velocity on leg stiffness. We also explored the relationship between leg stiffness and running joint work. Thirty-one healthy participants ran overground at 3 velocities (3.0, 4.0, 5.0 m⋅s-1), whilst carrying 3 load magnitudes (0%, 10%, 20% weight). Leg stiffness was derived using the direct kinetic-kinematic method. Joint work data was previously reported in a separate study. Linear models were used to establish relationships between leg stiffness and load magnitude, velocity, and joint work. Our results found that leg stiffness did not increase with load magnitude. Increased leg stiffness was associated with reduced total joint work at 3.0 m⋅s-1, but not at faster velocities. The association between leg stiffness and joint work at slower velocities could be due to an optimal covariation between skeletal and muscular components of leg stiffness, and limb attack angle. When running at a relatively comfortable velocity, greater leg stiffness may reflect a more energy efficient running pattern. [ABSTRACT FROM AUTHOR]

The aim of this systematic review was to evaluate the impact of bilaterally symmetrical backpack systems borne on the posterior trunk on walking biomechanics, as backpacks represent the most prevalent method of load carriage in the military and civilian population. A search of electronic databases was performed for studies that only investigated posteriorly-borne backpack carriage during level-grade walking (treadmill and over ground). Methodology of studies was assessed, and both meta-analysis and qualitative synthesis were completed. Fifty-four studies were included in this review. In summary, the available literature showed that backpack carriage in walking was associated with an increased trunk flexion angle, increased hip and ankle range of motion, increased vertical and horizontal ground reaction force, increased cadence, and reduced stride length. Several variations in backpack carriage protocols could explain between-study variations in results, including: walking speed, backpack carriage skill level, the use of a hip belt, and posterior displacement of the load away from the trunk. The findings of this systematic review will inform backpack carriage practices in the area of injury risk assessment and physical performance enhancement. [ABSTRACT FROM AUTHOR]

The musculoskeletal load in waste collection has been examined through simulated assessment of pulling and pushing bins as well as lifting and throwing rubbish bags. With the onset of mechanization, many of these tasks do not exist and workers are faced with other loads not previously assessed. The purpose of this study was to quantify the postures and muscle activity during mechanized waste collection work. Three subtasks of mechanized waste collection were identified, namely driving, bin collection, and egress and access of the vehicle. Spinal, shoulder, and upper limb kinematics along with surface electromyography from three muscles were collected during these tasks in a typical work shift. During driving and bin collection, participants adopted a head-extended, torso forward-flexed posture with frequent rotations of the head and neck. Egress and access of the vehicle produced substantially larger ranges of movement compared with driving and bin collection. The forward-flex, sitting posture can increase the risk of low back pain if there are undulations in the terrain and if this posture is adopted for prolonged periods. The frequent head and neck rotations can increase the incidence and severity of neck pain. Prolonged driving has been linked with an increased cardiometabolic risk and egress and access has increased risk of trips and falls from a height. Managers of waste collection workers should consider implementing interventions to reduce the exposure of this important workforce to the deleterious demands of their work. [ABSTRACT FROM AUTHOR]

Context: Accelerometer peak impact accelerations are being used to measure player physical demands in contact sports. However, their accuracy to do so has not been ascertained. Purpose: To compare peak-impact-acceleration data from an accelerometer contained in a wearable tracking device with a 3-dimensional motion-analysis (MA) system during tackling and bumping. Methods: Twenty-five semielite rugby athletes wore a tracking device containing a 100-Hz triaxial accelerometer (MinimaxX S4, Catapult Innovations, Australia). A single retroreflective marker was attached to the device, with its position recorded by a 12-camera MA system during 3 physical-collision tasks (tackle bag, bump pad, and tackle drill; N = 625). The accuracy, effect size, agreement, precision, and relative errors for each comparison were obtained as measures of accelerometer validity. Results: Physical-collision peak impact accelerations recorded by the accelerometer overestimated (mean bias 0.60 g) those recorded by the MA system (P < .01). Filtering the raw data at a 20-Hz cutoff improved the accelerometer's relationship with MA data (mean bias 0.01 g; P > .05). When considering the data in 9 magnitude bands, the strongest relationship with the MA system was found in the 3.0-g or less band, and the precision of the accelerometer tended to reduce as the magnitude of impact acceleration increased. Of the 3 movements performed, the tackle-bag task displayed the greatest validity with MA. Conclusions: The findings indicate that the MinimaxX S4 accelerometer can accurately measure physical-collision peak impact accelerations when data are filtered at a 20-Hz cutoff frequency. As a result, accelerometers may be useful to measure physical collisions in contact sports. [ABSTRACT FROM AUTHOR]