Validity and Reliability of Force-Time Characteristics Using a Portable Load Cell for the Isometric Midthigh Pull.

ABSTRACT: Pichardo, AW, Neville, J, Tinwala, F, Cronin, JB, and Brown, SR. Validity and reliability of force-time characteristics using a portable load cell for the isometric midthigh pull. J Strength Cond Res 38(1): 185-191, 2024-Many practitioners use the isometric midthigh pull (IMTP) to assess maximal strength in a safe, time-effective manner. However, expensive, stationary force plates are not always practical in a large team setting. Therefore, the purpose of this study was to establish the validity and between-session reliability of peak force, rate of force development (RFD), and impulse during an IMTP using 2 experimental protocols: a traditional fixed bar with a force plate (BarFP) and a flexible chain measured with a force plate (ChainFP) and a load cell (ChainLC). After a familiarization session, 13 resistance-trained men performed 3 trials of the BarFP condition and 3 trials of the chain-based conditions. The identical procedures were replicated twice more, with a week between each testing session. The main findings were (a) no RFD or impulse measures were found to achieve acceptable reliability across all methodological approaches and testing occasions; (b) peak force was reliable across all methods, with coefficient of variation ranging from 4.6 to 8.3%, intraclass correlation coefficient ranging from 0.94 to 0.98, and the least variability associated with the ChainLC condition; and (c) the ChainFP method was found to significantly underrepresent peak force by 4.8% (p < 0.05), with no significant differences between the ChainLC and BarFP methods. Therefore, the ChainLC would seem a valid, reliable, portable, and cost-effective alternative to force plates when assessing maximal isometric strength in the IMTP.

Effects of Resistance Training Methods on Golf Clubhead Speed and Hitting Distance: A Systematic Review.

ABSTRACT: Uthoff, A, Sommerfield, LM, and Pichardo, AW. Effects of resistance training methods on golf clubhead speed and hitting distance: A systematic review. J Strength Cond Res 35(9): 2651-2660, 2021-Resistance training is widely regarded within the golfing community to improve golf performance by increasing clubhead speed (CHS) and drive distance and can be classified into 3 categories: nonspecific, specific, and combined. However, it is currently unclear which resistance training methods are most effective in improving predictors of golf performance. Therefore, the purpose of this review is to compare the effectiveness of nonspecific, specific, and combined strength training methods on CHS and drive distance. A systematic search strategy was performed using the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines to identify eligible articles through PubMed, SPORTDiscus, MEDLINE (EBSCO), and Google Scholar. The searches identified 4,557 potentially relevant results, with 20 studies that met the inclusion criteria and were included in the final review. Thirteen studies investigated nonspecific resistance training, one study investigated specific resistance training, and 7 studies investigated combined resistance training. Collectively, resistance training positively impacts golf CHS and hitting distance, but adaptations vary depending on the type and intensity of training, as well as subject's characteristics. Using a combination of nonspecific and golf-specific training (average increase of 4.1% CHS and 5.2% hitting distance) seems to enhance golf performance more than nonspecific strength training (average increase of 1.6% CHS and 4.8% hitting distance). Eight-week programs including golf-specific movements at high velocities for 3 to 4 sets of 5 to 15 repetitions are the most effective in increasing CHS and hitting distance. Future research investigating how golf-specific training influences CHS and hitting distance in various subgroups may provide further insight regarding prescription of this training type.

Effects of Combined Resistance Training and Weightlifting on Injury Risk Factors and Resistance Training Skill of Adolescent Males.

ABSTRACT: Pichardo, AW, Oliver, JL, Harrison, CB, Maulder, PS, Lloyd, RS, and Kandoi, R. Effects of combined resistance training and weightlifting on injury risk factors and resistance training skill of adolescent males. J Strength Cond Res 35(12): 3370-3377, 2021-The purpose of this study was to investigate the effects of resistance training with or without weightlifting on risk factors for injury and resistance training skill in circa-peak height velocity boys. Sixty-seven boys (aged 12-14 years) from a local secondary school were divided into 3 groups: combined resistance training (CRT), combined resistance training with weightlifting movements (CRT&WL), or a control group (CON). Experimental groups completed twice-weekly training programs over the course of an academic year. The tuck jump assessment, asymmetry measures for single-leg horizontal jump, isometric midthigh pull, and the Star Excursion Balance Test, and resistance training skill were measured pre-, mid-, and post-intervention. Only the CRT group significantly improved tuck jump assessment score pre- to post-test (p = 0.006, -20.4%, d = -0.39) but there were no clear effects on asymmetry measures for any group. Both groups significantly improved resistance training skill from pre- to post-test (CRT&WL: p = 0.002, 17.6%, d = 1.00; CRT: p = 0.026, 9.2%, d = 0.53). This study suggests that a school-based CRT program may provide significant improvements in jump landing kinematics, whereas the inclusion of weightlifting movements may provide greater improvements in resistance training skill.

An Accessible, 16-Week Neck Strength Training Program Improves Head Kinematics Following Chest Perturbation in Young Soccer Athletes.

CONTEXT: Neck size and strength may be associated with head kinematics and concussion risks. However, there is a paucity of research examining neck strengthening and head kinematics in youths. In addition, neck training is likely lacking in youth sport due to a perceived inadequacy of equipment or time. OBJECTIVE: Examine neck training effects with minimal equipment on neck strength and head kinematics following chest perturbations in youth athletes. DESIGN: Single-group, pretest-posttest case series. SETTING: Athlete training center. PARTICIPANTS: Twenty-five (14 men and 11 women) youth soccer athletes (9.8 [1.5] y). INTERVENTION: Sixteen weeks of twice-weekly neck-focused resistance training utilizing bands, body weight, and manual resistance. MAIN OUTCOME MEASURES: Head kinematics (angular range of motion, peak anterior-posterior linear acceleration, and peak resultant linear acceleration) were measured by an inertial motion unit fixed to the apex of the head during torso perturbations. Neck-flexion and extension strength were assessed using weights placed on the forehead and a plate-loaded neck harness, respectively. Neck length and circumference were measured via measuring tape. RESULTS: Neck extension (increase in median values for all: +4.5 kg, +100%, P < .001; females: +4.5 kg, +100%, P = .002; males: +2.2 kg, +36%, P = .003) and flexion (all: +3.6 kg, +114%, P < .001; females: +3.6 kg, +114%, P = .004; males: +3.6 kg, +114%, P = .001) strength increased following the intervention. Men and women both experienced reduced perturbation-induced head pitch (all: -84%, P < .001). However, peak resultant linear acceleration decreased in the female (-53%, P = .004), but not male (-31%, P = 1.0) subgroup. Preintervention peak resultant linear acceleration and extension strength (R2 = .21, P = .033) were the closest-to-significance associations between head kinematics and strength. CONCLUSIONS: Young athletes can improve neck strength and reduce perturbation-induced head kinematics following a 16-week neck strengthening program. However, further research is needed to determine the effect of improved strength and head stabilization on concussion injury rates.

Effects of Combined Resistance Training and Weightlifting on Motor Skill Performance of Adolescent Male Athletes.

Pichardo, AW, Oliver, JL, Harrison, CB, Maulder, PS, Lloyd, RS, and Kandoi, R. Effects of combined resistance training and weightlifting on motor skill performance of adolescent male athletes. J Strength Cond Res 33(12): 3226-3235, 2019-Resistance training and weightlifting are regarded as safe and effective training methods for youth. However, no studies have examined the effects of a year-long resistance training program using weightlifting movements on strength, speed, or power. Therefore, the purpose of this study was to determine the long-term effects of combined resistance training (traditional strength training + plyometrics) with or without weightlifting movements on motor skill performance of adolescent males. Fifty-nine males aged 12-14 years were matched by maturity and allocated to a combined resistance training or a combined resistance training with weightlifting group. Each group completed 28 total weeks of training over an academic year. Pre-, mid- (14 weeks of training), and post-training (28 weeks of training) tests included the resistance training skills battery quotient (RTSQ), absolute isometric midthigh pull peak force (IMTPABS) and ratio-scaled isometric midthigh pull peak force (IMTPREL), countermovement jump, horizontal jump, and 10-, 20-, and 30-m sprint. Repeated-measure analysis of variance revealed that there were no significant between-group responses, but all variables improved significantly within-group. Both groups made small-moderate improvements in RTSQ, IMTPABS, and IMTPREL after the first 14 training weeks (d = 0.45-0.86), whereas small-moderate improvements in lower body power, upper body power, and speed were made after the second 14 training weeks (d = 0.30-0.95). Both groups made small-moderate improvements in all performance variables after 28 weeks of training. These findings highlight the importance of establishing movement competency and strength as a foundation for the subsequent development of power. Furthermore, these findings may help practitioners understand the time course of certain adaptations following a long-term periodized plan for adolescent males.

The Influence of Maturity Offset, Strength, and Movement Competency on Motor Skill Performance in Adolescent Males.

This study aimed to examine the extent to which maturity offset, strength, and movement competency influences motor skill performance in adolescent boys. One hundred and eight secondary school boys completed anthropometric and physical testing on two non-consecutive days for the following variables: Maturity offset, isometric mid-thigh pull absolute (IMTPABS) and relative (IMTPREL) peak force, resistance training skills quotient, 10-, 20-, and 30-m sprint time, countermovement jump height, horizontal jump distance, anaerobic endurance performance, and seated medicine ball throw (SMBT). The IMTPREL displayed significant small to large correlations with all performance variables (r = 0.27-0.61), whereas maturity offset was significantly correlated with IMTPABS (r = 0.69), sprint (r = 0.29-0.33), jump (r = 0.23-0.34), and SMBT (r = 0.32). Absolute and relative strength were the strongest predictors of all performance variables and combined with maturity to explain 21%-76% of the variance. Low and average relative strength boys were nearly eight times (odds ratio: 7.80, confidence interval: 1.48-41.12, p < 0.05) and nearly four times (odds ratio: 3.86, confidence interval: 0.95-15.59, p < 0.05) more likely to be classified as lower competency compared to high relative strength boys. Relative strength has more influence on motor skill performance than maturity when compared with movement competency.