Paul Macadam

Acute kinematic and kinetic adaptations to wearable resistance during sprint acceleration

Abstract Macadam, P, Simperingham, KD, and Cronin, JB. Acute kinematic and kinetic adaptations to wearable resistance during sprint acceleration. J Strength Cond Res 31(5): 1297–1304, 2017—Wearable resistance (WR) in the form of weighted vests and shorts enables movement-specific sprint running to be performed under load. The purpose of this study was to determine the acute changes in kinematics and kinetics when an additional load equivalent to 3% body mass (BM) was attached to the anterior or posterior surface of the lower limbs during sprint running. Nineteen male rugby athletes (age: 19.7 ± 2.3 years; body mass: 96.1 ± 16.5 kg; height: 181 ± 6.5 cm) volunteered to participate in the study. Subjects performed six 20 m sprints in a randomized fashion wearing no resistance or 3%BM affixed to the anterior (quadriceps and tibialis anterior) or posterior (hamstring and gastrocnemius) surface of the lower limbs (2 sprints per condition). Optojump and radar were used to quantify sprint times, horizontal velocity, contact and flight times, and step length and frequency. A repeated measures analysis of variance with post hoc contrasts was used to determine differences (p ⩽ 0.05) between conditions. No significant differences were found between the anterior and posterior WR conditions in any of the variables of interest. There was no significant change in sprint times over the initial 10 m, however, the 10–20 m split times were significantly slower (−2.2 to −2.9%) for the WR conditions compared with the unloaded sprints. A significant change in the relative force–velocity (F–v) slope (−10.5 to −10.9%) and theoretical maximum velocity (V 0) (−5.4 to −6.5%) was found, whereas a nonsignificant increase in theoretical maximum force (F 0) (4.9–5.2%) occurred. Wearable resistance of 3%BM may be a suitable training modality to enhance sprint acceleration performance by overloading the athlete without negatively affecting sprint running technique.

Physical and physiological demands of futsal

Futsal, the 5-a-side version of soccer (i.e. 1 goalkeeper and 4 outfield players), was introduced in 1930 and continues to grow in popularity around the world. Competitive games comprise of two 20-min periods of high-intensity and intermittent activities requiring substantial physical, tactical, and technical efforts from the players. A greater understanding of the physical and skill requirements will aid the development of futsal and enable practitioners to undertake appropriate training regimes for the demands of the sport. The objective of this review is to examine key aspects of futsal such as match analysis, physiological demands, energy requirements, fitness measurements, and skill requirements. Futsal players experience fatigue as the game progresses due to the high-intensity nature of the game and the repeated maximal sprint efforts required. The intermittent nature of the sport necessitates the use of aerobic and anaerobic energy pathways throughout exercise. Therefore, a futsal player needs to have a great capacity of intermittent endurance, repeated sprint ability, and leg power, while technical aspects include the ability of high level shooting and passing skills, agility and coordination. Future research is warranted to help practitioners develop more specific tests into futsal performance, especially with regards skill.

Effects of upper and lower body wearable resistance on spatio-temporal and kinetic parameters during running

ABSTRACT Wearable resistance training involves added load attached directly to the body during sporting movements. The effects of load position during running are not yet fully established. Therefore, the purpose of this research was to determine spatio-temporal and kinetic characteristics during submaximal running using upper, lower and whole-body wearable resistance (1–10% body mass (BM)). Twelve trained male runners completed eight 2-min treadmill running bouts at 3.9 m/s with and without wearable resistance. The first and last bouts were unloaded, while the middle 6 were randomised wearable resistance conditions: upper body (UB) 5% BM, lower body (LB) 1%, 3%, 5% BM and whole body (WB) 5%, 10% BM. Wearable resistance of 1–10% BM resulted in a significant increase in heart rate (5.40–8.84%), but minimal impact on spatio-temporal variables. Loads of 5% BM and greater caused changes in vertical stiffness, vertical and horizontal force, and impulse. Functional and effective propulsive force (2.95%, 2.88%) and impulse (3.40%, 3.38%) were significantly (p < 0.05) greater with LB5% than UB5%. Wearable resistance may be used to increase muscular kinetics during running without negatively impacting spatio-temporal variables. The application of these findings will vary depending on athlete goals. Future longitudinal studies are required to validate training contentions.

Forearm wearable resistance effects on sprint kinematics and kinetics

OBJECTIVES Arm swing is a distinctive characteristic of sprint-running with the arms working in a contralateral manner with the legs to propel the body in a horizontal direction. The purpose of this study was to determine the acute changes in kinematics and kinetics when wearable resistance (WR) of 1kg (equivalent to ∼1% body mass) was attached to each forearm during over ground short distance (20m) maximal sprint-running. DESIGN Cross-sectional study. METHODS Twenty-two male amateur rugby athletes (19.4±0.5years; 97.0±4.8kg; 180.4±7.2cm) volunteered to participate in the study. Radar and Optojump were used to examine kinematic and kinetics between WR and unloaded sprint-running conditions. RESULTS No significant (p<0.05) differences were found at 2m or 5m between conditions, however, the WR condition resulted in a significant increase in 10m, 20m and 10-20m split time (all, ∼2%, small effect size) compared to the unloaded condition. Significant decreases were also found in theoretical maximum velocity (V0) (-1.4%, small effect size) and relative peak horizontal power production (Pmax) (-5.5%, small effect size). Step length (2.1%, small effect size) and contact time (6.5%, medium effect size) were significantly increased, while step frequency (-4.1%, small effect size) and flight time (-5.3%, medium effect size) were significantly decreased. CONCLUSIONS WR forearm loading provides a movement specific overload of the arms which significantly alters step kinematics and sprint times ≥10m.

Key movements and skills of wicket-keepers in one day international cricket

The wicket-keeper is a specialist position within the fielding unit of cricket; however, this position has not been afforded a great deal of attention in empirical research. Therefore, the purpose of this study was to identify the movement and skill demands of wicket-keeping in one day international cricket through video analysis. Television footage of eight games (16 innings) from the 2011 one day international World Cup was analysed using the video analysis package SportsCode. The variables of interest included 7 movement-related activities and 15 skills-related activities from a mean innings of 41 ± 11 overs. Following the crouch action, which is required every ball, the highest average (times per innings) movement activities were the lateral step (78), lateral shuffle (53) and running to the stumps (27). The highest average skill activities were to receive the ball from the field (42), throw underarm (32) and take the ball following the bowler’s delivery (24). The most important skill for a wicket-keeper is the ability to catch the ball, be it with one or both hands, either from an almost stationary position standing close to the batsman, or following an explosive movement such as a dive or sprint. A wicket-keeping specific catching test should reflect this, and include a multitude of catching scenarios. Due to the fact that the wicket-keeper performs repetitive movement in multiple planes, training and movement assessments should take this into account. The findings from this study can assist practitioners in understanding assessment, program and skill development aspects of the wicket-keeper position.

An investigation into the influence of score differential on the physical demands of international women’s rugby sevens match play

ABSTRACT This study explores whether the score differential in winning games influenced the physical demands of match play in women’s rugby seven players. Fifteen members from a highly ranked international team (mean ± SD, 24.3 ± 3.87 years, 168 ± 7.15 cm, 67.5 ± 6.31 kg) participated in this study. Winning score differentials were classified as either small (<21 points) or large (>21 points) and global positional system running data along with match play activities were analysed to identify whether differences exist. Total distances covered were moderately greater in high score differential games (mean difference, ±99% confidence limits, 3.8, ±5.2 m·min−1). Small differences (high – low) were also observed for distance covered at the following speeds: 2–3.5 m·s−1 (1.3, ±3.4 m·min−1), 5–6 m·s−1 (0.8, ±1.5 m·min−1) and ≥6 m·s−1 (1.4, ±1.6 m·min−1). There were a moderately greater numbers of missed tackles (mean count 0.2) and lineouts (mean count 0.5) in low score differential versus high score differential games. Greater winning margins were associated with greater running demands and fewer match activity demands. It is suggested that specific recovery protocols should be considered for matches that have either higher running or match activity demands.

Key match activities of different fielding positions and categories in one-day international cricket

ABSTRACT Fielding has gained considerable importance in the game of cricket; however, there is a paucity of research in this area compared to batting and bowling. The purpose of this study therefore was to quantify the movement demands of one-day international (ODI) fielding. Television footage of eight games (16 innings) from the 2011 ODI World Cup was analysed using the video analysis package SportsCode. The variables of interest included 16 fielding-related activities and two efficiency calculations. These variables were calculated for fielding positions (excluding wicketkeepers) and categories of fielding. There were on average 177 ± 52 fielding contacts and 12 ± 6 fielding mistakes per innings. The activity in the field was split between the fielding categories: 20% close fielding, 51% inner circle fielding and 29% outer circle fielding. The positions with the most fielding activity per innings were bowler (26), cover (24), backward point (14), mid-off (14) and midwicket (14). Understanding the movement demands of cricket fielding provides value to coaches when designing assessments, and individualising training programmes to match positional and categorical (close, inner and outer) fielding demands.

Acute kinematic and kinetic adaptations to wearable resistance during vertical jumping

Abstract One variation of vertical jump (VJ) training is resisted or weighted jump training, where wearable resistance (WR) enables jumping to be overloaded in a movement specific manner. A two-way analysis of variance with Bonferroni post hoc contrasts was used to determine the acute changes in VJ performance with differing load magnitudes and load placements. Kinematic and kinetic data were quantified using a force plate and contact mat. Twenty sport active subjects (age: 27.8 ± 3.8 years; body mass (BM): 70.2 ± 12.2 kg; height: 1.74 ± 0.78 m) volunteered to participate in the study. Subjects performed the counter movement jump (CMJ), drop jump (DJ) and pogo jump (PJ) wearing no resistance, 3% or 6% BM affixed to the upper or lower body. The main finding in terms of the landing phase was that the effect of WR was non-significant (P > .05) on peak ground reaction force. With regard to the propulsive phase the main findings were that for both the CMJ and DJ, WR resulted in a significant (P < .05) decrease in jump height (CMJ: −12% to −17%, DJ: −10% to −14%); relative peak power (CMJ: −8% to −17%, DJ: −7% to −10%); and peak velocity (CMJ: −4% to −7%, DJ: −3% to −8%); while PJ reactive strength index was significantly reduced (−15% to −21%) with all WR conditions. Consideration should be given to the inclusion of WR in sports where VJ’s are important components as it may provide a novel movement specific training stimulus. Highlights WR of 3 or 6 % BM provided a means to overload the subjects in this study resulting in decreased propulsive power and velocity that lead to a reduced jump height and landing force. Specific strength exercises that closely mimic sporting performance are more likely to optimise transference, therefore WR with light loads of 3–6% body mass (BM)appear a suitable tool for movement specific overload training and maximising transference to sporting performance. Practitioners can safely load their athletes with upper or lower body WR of 3–6% BM without fear of overloading the athletesover and above the landing forces they are typically accustomed too. As a training stimulus it would seem the WR loading provides adequate overload and athletes should focus on velocity of movement to improve power output and jump height i.e. take-off velocity.

Redistributing load using wearable resistance during power clean training improves athletic performance

Abstract A popular method to improve athletic performance and lower body power is to train with wearable resistance (WR), for example, weighted vests. However, it is currently unknown what training effect this loading method has on full-body explosive movements such as the power clean. The purpose of this study was to determine what effects WR equivalent to 12% body mass (BM) had on the power clean and countermovement jump (CMJ) performance. Sixteen male subjects (age: 23.2 ± 2.7 years; BM: 90.5 ± 10.3 kg) were randomly assigned to five weeks of traditional (TR) power clean training or training with 12% BM redistributed from the bar to the body using WR. Variables of interest included pre and post CMJ height, power clean one repetition maximum (1RM), peak ground reaction force, power output (PO), and several bar path kinematic variables across loads at 50%, 70%, and 90% of 1RM. The main findings were that WR training: (1) increased CMJ height (8.7%; ES = 0.53) and 1RM power clean (4.2%; ES = 0.2) as compared to the TR group (CMJ height = −1.4%; 1RM power clean = 1.8%); (2) increased PO across all 1RM loads (ES = 0.33–0.62); (3) increased barbell velocity at 90% 1RM (3.5%; ES = 0.74) as compared to the TR group (−4.3%); and (4) several bar path kinematic variables improved at 70% and 90% 1RM loads. WR power clean training with 12% BM can positively influence power clean ability and CMJ performance, as well as improve technique factors.