Impact of Harness Attachment Point on Kinetics and Kinematics During Sled Towing

Speed Training Practices of Brazilian Olympic Sprint and Jump Coaches: Toward a Deeper Understanding of Their Choices and Insights (Part II)

This is the second article in a three-article collection regarding the plyometric, speed, and resistance training practices of Brazilian Olympic sprint and jump coaches. Here, we list and describe six out of the ten speed training methods most commonly employed by these experts to enhance the sprinting capabilities of their athletes. Maximum speed sprinting, form running, resisted sprinting, overspeed running, uphill and downhill running, and sport-specific movement methods are critically examined with reference to their potential application in different sport contexts. In an era when sprint speed is of critical importance across numerous sports, practitioners can employ the methods outlined here to design efficient training programs for their athletes.

Resisted sprint training with partner towing improves explosive force and sprint performance in young soccer players - a pilot study

The purpose of this study was to examine the effects of non-resisted (NRS) and partner-towing resisted (RS) sprint training on legs explosive force, sprint performance and sprint kinematic parameters. Sixteen young elite soccer players (age 16.6 ± 0.2 years, height 175.6 ± 5.7 cm, and body mass 67.6 ± 8.2 kg) were randomly allocated to two training groups: resisted sprint RS (n = 7) and non-resisted sprint NRS (n = 9). The RS group followed a six-week sprint training programme consisting of two "sprint training sessions" per week in addition to their usual soccer training. The NRS group followed a similar sprint training programme, replicating the distances of sprints but without any added resistance. All players were assessed before and after training: vertical and horizontal jumping (countermovement jump (CMJ), squat jump (SJ), and 5-jump test (5JT)), 30 m sprint performance (5, 10, and 20 m split times), and running kinematics (stride length and frequency). In the RS group significant (p < 0.05) changes were: decreased sprint time for 0-5 m, 0-10 m and 0-30 m (-6.31, -5.73 and -2.00%; effect size (ES) = 0.70, 1.00 and 0.41, respectively); higher peak jumping height (4.23% and 3.59%; ES = 0.35 and 0.37, for SJ and CMJ respectively); and 5JT (3.10%; ES = 0.44); and increased stride frequency (3.96%; ES = 0.76). In the NRS group, significant (p < 0.05) changes were: decreased sprint time at 0-30 m (-1.34%, ES = 0.33) and increased stride length (1.21%; ES = 0.17). RS training (partner towing) for six weeks in young soccer players showed more effective performances in sprint, stride frequency and lower-limb explosive force, while NRS training improved sprint performance at 0-30 m and stride length. Consequently, coaches and physical trainers should consider including RS training as part of their sprint training to ensure optimal sprint performance.

The Effects of Sprint vs. Resisted Sled-Based Training; an 8-Week in-Season Randomized Control Intervention in Elite Rugby League Players

The aim of the current study was to examine the efficacy of resisted sled-based training compared to traditional unresisted sprint training in terms of mediating improvements in speed, agility, and power during an eight-week period of in-season training in elite rugby league players. Participants were randomly separated into either resisted sled or traditional sprint-based training groups and they completed an eight-week in-season training block with training prescribed based on the group to which they were assigned. Measures of 5 m, 10 m, and 20 m sprint times in addition to countermovement jump height and 505-agility test time were measured at baseline, four-weeks and eight-weeks. For sprint-based outcomes, although both groups improved significantly, there were no statistical differences between the two training methods. However, at the eight-week time point there were significant improvements in 505-agility test (sprint group: baseline = 2.45 and eight-weeks = 2.42 s/sled group: baseline = 2.43 and eight-weeks = 2.37 s) and countermovement jump (sprint group: baseline = 39.18 and eight-weeks = 39.49 cm/sled group: baseline = 40.43 and eight-weeks = 43.07 cm) performance in the sled training group. Therefore, the findings from this investigation may be important to strength and conditioning coaches working in an elite rugby league in that resisted sled training may represent a more effective method of sprint training prescription.

Postactivation Potentiation Effect of Heavy Sled Towing on Subsequent Sprints

ABSTRACT

Williams, JJ, Heron, R, Spradley, B, and Saracino, P. Postactivation potentiation effect of heavy sled towing on subsequent sprints. J Strength Cond Res 35(5): 1229-1233, 2021-Recent research supports heavy sled towing as a tool used to improve subsequent sprints as part of postactivation potentiation (PAP) protocols. The purpose of this study was to examine the effect of heavy sled towing using a velocity decrement (Vdec) on subsequent unloaded sprinting in high school football (soccer) athletes sprinting on artificial turf. A sled load equating to a 40-50% Vdec range was used (66-70% body mass). Fifteen (n = 9 boys and n = 6 girls) high school football players volunteered for this study. The sled-towing intervention consisted of a dynamic warm-up, 3 submaximal sprint efforts (50, 75, and 95%), and 3 maximum speed 15-m sled sprints, separated by 2-minute rests, of which the fastest time was recorded for analysis. Peak preintervention 15-m baseline sprint times were compared with peak post sled-towing 15-m sprint times using a paired samples t-test. Thirteen of 15 athletes ran faster peak post sled-towing sprint times than peak preintervention baseline sprint times (9 boys and 4 girls). On average, peak post sled-towing sprint times (2.60 ± 0.10 seconds) were 0.10 seconds faster (p < 0.0001; Cohen's d = 0.92) than peak preintervention baseline sprint times (2.70 ± 0.09 seconds). This research established that sled-towing protocols using loads corresponding to Vdec of 40-50% significantly improved subsequent sprints in high school football (soccer) athletes running on artificial turf.

Effect of Velocity-Based Loading on Acceleration Kinetics and Kinematics During Sled Towing

ABSTRACT

Bentley, I, Sinclair, JK, Atkins, SJ, Metcalfe, J, and Edmundson, CJ. Effect of velocity-based loading on acceleration kinetics and kinematics during sled towing. J Strength Cond Res 35(4): 1030-1038, 2021-Sled towing (ST) provides an external load in the form of a sled towed using a shoulder or waist harness and cord behind the athlete. Loading strategies have varied greatly between studies, and despite many investigations, there is little agreement on the optimum sled loading to develop the acceleration phase. The aim of this study was to investigate the kinetics and kinematics of velocity-based ST during the acceleration phase of sprinting. Twelve academy rugby league players performed a series of 6-m sprints in different conditions; uninhibited, 10, 15, and 20% velocity decrement (VDec). Sagittal plane kinematics and kinetic measures were examined using 1-way repeated-measures analysis of variance. Results indicated that ST affected trunk, knee, and ankle joint kinematics (p < 0.05). Peak knee flexion increased as sled loads increased (p < 0.05), which may enable athletes to lower their center of mass and increase their horizontal force application. Net horizontal and propulsive impulse measures were greater in all sled conditions (p < 0.05), which increased significantly because sled loadings were heavier. In conclusion, this study highlights the effects of differential loads to help coaches understand acute kinetics and kinematic changes to improve the planning of sprint training.

Kinematics and Kinetics of Bulgarian-Bag-Overloaded Sprints in Young Athletes

Background: Effective sprinting requires large acceleration capabilities. To accelerate, large amount of force must be produced and applied effectively. The use of different implements such as sleds and vests can increase the amount of force produced and alter sprinting effectiveness. We propose the use of increasing overload via the Bulgarian Bag (BB) as a means to modify athletes’ sprint and acutely increase force and power production. Methods: 24 young athletes performed three sprints over 20 m in three different conditions: unloaded (BW) and loaded with BB weighing 2.5% (BB2.5) and 5% (BB5) of the athlete’s body mass. Sprint times at 2.5, 5, 10, 15, and 20 m were acquired and used to compute the force–velocity relationship for the sprints. Maximal velocity (V0), peak force (F0), peak power (PP), and decrease in ratio of force (D_RF) were computed. Results: the additional load caused a decrease in sprint times (p < 0.05) and V0 (p = 0.028), conversely no differences were found for F0 (p = 0.21), PP (p = 0.50), and D_RF (p = 0.83). Conclusions: Based on those findings, BB can be an alternative method to effectively overload sprint training toward improving sprinting performance.

The Biomechanics and Applications of Strongman Exercises: a Systematic Review

Background

The sport of strongman is becoming increasingly popular, catering for females, lightweight, and Masters competitors, with strongman exercises also being used by strength and conditioning coaches for a range of athletic groups. Thus, a systematic review was conducted to examine researchers’ current understanding of the biomechanics of strongman exercises, with a view to improve strongman athlete performance, provide biomechanical evidence supporting the transferability of strongman exercises to strength and conditioning/rehabilitation programs, and identify gaps in the current knowledge of the biomechanics of strongman exercises.

Methods

A two-level search term strategy was used to search five databases for studies relevant to strongman exercises and biomechanics.

Results

Eleven articles adherent to the inclusion criteria were returned from the search. The studies provided preliminary biomechanical analysis of various strongman exercises including the key biomechanical performance determinants of the farmer’s walk, heavy sled pull, and tire flip. Higher performing athletes in the farmer’s walk and heavy sled pull were characterized by a greater stride length and stride rate and reduced ground contact time, while higher performing athletes in the tire flip were characterized by a reduced second pull phase time when compared with lower performing athletes. Qualitative comparison of carrying/walking, pulling and static lifting strongman, traditional weight training exercises (TWTE), and common everyday activities (CEA), like loaded carriage and resisted sprinting, were discussed to further researchers’ understanding of the determinants of various strongman exercises and their applications to strength and conditioning practice. A lack of basic quantitative biomechanical data of the yoke walk, unilateral load carriage, vehicle pull, atlas stone lift and tire flip, and biomechanical performance determinants of the log lift were identified.

Conclusions

This review has demonstrated the likely applicability and benefit of current and future strongman exercise biomechanics research to strongman athletes and coaches, strength and conditioning coaches considering using strongman exercises in a training program, and tactical operators (e.g., military, army) and other manual labor occupations. Future research may provide a greater understanding of the biomechanical determinants of performance, potential training adaptations, and risks expected when performing and/or incorporating strongman exercises into strength and conditioning or injury rehabilitation programs.