Jamie J. Ghigiarelli

Purpose: The aim of this study was to assess within-session reliability and concurrent validity of a wireless surface electromyography device (MR EMG) relative to a wireless criterion system (Delsys Trigno) during dynamic leg extension at varying loading intensities. Methods: Thirty-one resistance-trained adults performed four repetitions at 30%, 60%, and 90% of their predicted one-repetition maximum (1RM) on the plate-loaded leg extension machine, with EMG amplitude recorded simultaneously by both systems for the vastus lateralis (VL) and vastus medialis obliquus (VMO). Root mean square (RMS) amplitudes were normalized to maximal voluntary isometric contraction and compared across devices using intraclass correlation coefficients (ICC), coefficients of variation (CV%), standard error of measurement, Pearson correlations, and Bland–Altman analyses. Results: Both devices demonstrated excellent within-session reliability (ICC = 0.92–0.97; CV = 7.8–11.3%). Validity differed by muscle. Across all loads, VMO agreement was good (ICC = 0.82–0.85; r = 0.83–0.86), while VL agreement was moderate (ICC = 0.53–0.57; r = 0.54–0.64). Bland–Altman analyses revealed systematic positive bias across all conditions, with proportional bias present for the VL but absent for the VMO. Conclusions: MR EMG demonstrated excellent within-session reliability but muscle-dependent concurrent validity, with good VMO agreement and moderate VL agreement with the criterion system.

Background: Heavy resisted sprint training (RST) improves horizontal force, with growing support for individualized programs guided by force-velocity (FV) profiling. Objective: This quasi-experimental design compared the effects of two heavy RST programs on force-velocity-power output in collegiate female volleyball players. Methods: Based on baseline individual FV slope (SFV), 15 players completed a 12-week RST program in one of two groups: very heavy (GH, SFV0.92, 75% velocity decrement [VDEC], n=9) or very heavy-to-moderate (GH-M, SFV0.92, 75%–50%–25% VDEC, n=6). Thirty-meter sprint performance was assessed across eight timepoints (T1-T8). Sprinting variables were measured using a speed laser device, and load-velocity profiles were derived using the EXER-GENIE® resisted sprints. The primary outcomes were peak force (F0), peak velocity (V0), and peak power (PMAX). Repeated measures ANCOVAs, with baseline scores as covariates, tested for time, group, and interaction effects. Results: Significant main effects for F0 were observed over time (p=.028), between groups (p=.001), and group x time interaction (p=.010). The GH group had significantly higher F0 than the GH-M group from T2-T8 (p.05), with increases from baseline to T2-T4, T6, and T8 (all p.05). No significant changes occurred in the GH-M group. No main effects were detected for V0; however, the GH group demonstrated significant fluctuations across time. For PMAX, significant effects were observed for group (p.01) and interaction (p=.004). The GH group had significantly higher PMAX than the GH-M group from T2-T8 (p.05), and increased from baseline to all points T2-T8 (p.05), whereas the GH-M group showed no changes. Conclusions: Very heavy RST elicited greater improvements in both F0 and PMAX compared to heavy-to-moderate progression. These findings suggest tailoring sprint training to individual FV deficits may optimize sprint-specific adaptations.

Sport performance coaches use a range of modalities to apply a horizontal force (F_h) to athletes during resisted sprint training (RST). These modalities include parachutes, weighted vests, pulley devices, motored tethered devices, and, most notably, weighted sleds. Despite the widespread use of these devices, the resistance forces of the pulley devices have not been evaluated for reliability and accuracy. Therefore, the primary aim of this study is to quantify the F_h of a commercially available pulley device (EXER-GENIE®) and determine how resistance force is related to the load settings on the device. The secondary aim is to identify the differences in the F_h values between three EXER-GENIE® devices that use 36 m and 60 m ropes. The F_h values in the Newtons (N) of the three EXER-GENIE® devices were analyzed using a motorized winch, a lead acid battery, and an S-beam load cell. Four 10 s winch-driven trials were performed using 15 different EXER-GENIE® loads, ranging from 0.028 kg to 3.628 kg, employing two different 36 m devices and one 60 m device. The mean ± standard deviation for F_h was reported across the four trials for each load setting. All devices produced similar F_h values across lighter load settings (loads ≤0.141 kg). However, at heavier loads (loads ≥0.226 kg), the 60 m device had F_h values 50–85 N greater than those of the 36 m device. The coefficient of variation across the four trials was extremely high at light loads but sharply decreased to F_h values and EXER-GENIE® load indicated a strong positive relationship between load and F_h values across all devices (R²= 0.96–0.99). Caution should be exercised when using identical loads on the different-length pulley devices, as the 60 m device produced greater F_h values than the 36 m devices at load settings higher than 0.226 kg. These results can provide coaches and practitioners with a better understanding of the magnitude of resistance that is applied when prescribing EXER-GENIE® devices for higher training loads.

L-citrulline serves as a nitric oxide precursor with the potential to increase blood flow and improve resistance exercise performance, yet more research is needed to examine its ergogenic potential. To examine the effect of L-citrulline supplementation on resistance exercise performance, muscle oxygenation, and the subjective perception of effort, energy, focus, fatigue, and muscle pump, eighteen resistance-trained men (n = 11) and women (n = 7) (21.4 ± 1.8 years; 172.3 ± 7.5 cm; 76.9 ± 10.8 kg) were randomly assigned for supplementation with 8 g of L-citrulline (CIT) or a placebo (PL) in a cross-over fashion one hour prior to testing. Participants completed an isometric mid-thigh pull test (IMTP), a ballistic bench press protocol [two sets of two repetitions at 75% 1-repetition maximum (1 RM) with maximum ballistic intent], and a strength-endurance bench press protocol [five repetition-maximum sets at 75% 1RM]. Barbell velocity and power were measured via a linear position transducer during the ballistic protocol, while the repetitions completed, volume load and muscle oxygenation were quantified during the strength-endurance protocol. Subjective measures were assessed at the baseline and immediately pre- and post-exercise. Repeated measures of the analysis of variance and Bayesian equivalents revealed no significant interactions, providing evidence favoring the null hypothesis (BF10 < 1) for IMTP (PL 497.5 ± 133.6 vs. CIT 492.5 ± 129.4 N), barbell velocity, and power, and repetitions completed (PL 36.7 ± 7.2 vs. CIT 36.9 ± 8.1 repetitions). There were also no significant interactions for muscle oxygenation parameters or subjective measures except perceived fatigue. Women reported greater fatigue across all time points compared to men (~1.88 au, p = 0.045, BF10 = 0.2). The results indicate that a single 8 g dose of L-citrulline did not enhance isometric force production, muscle endurance, or muscle oxygenation parameters during the protocol implemented in this study.

This study examined the level of agreement (Pearson product-moment correlation [r_P]), within- and between-day reliability (intraclass correlation coefficient [ICC]), and minimal detectable change of the Musclelab^TM Laser Speed (MLS) device on sprint time and force–velocity–power profiles in Division II Collegiate athletes. Twenty-two athletes (soccer = 17, basketball = 2, volleyball = 3; 20.1 ± 1.5 y; 1.71 ± 0.11 m; 70.7 ± 12.5 kg) performed three 30-m (m) sprints on two separate occasions (seven days apart). Six time splits (5, 10, 15, 20, 25, and 30 m), horizontal force (HZT F₀; N∙kg⁻¹), peak velocity (V_MAX; m∙s⁻¹), horizontal power (HZT P₀; W∙kg⁻¹), and force–velocity slope (S_FV; N·s·m⁻¹·kg⁻¹) were measured. Sprint data for the MLS were compared to the previously validated MySprint (MySp) app to assess for level of agreement. The MLS reported good to excellent reliability for within- and between-day trials (ICC = 0.69–0.98, ICC = 0.77–0.98, respectively). Despite a low level of agreement with HZT F₀ (r_P = 0.44), the MLS had moderate to excellent agreement across nine variables (r_p = 0.68–0.98). Bland–Altman plots displayed significant proportional bias for V_MAX (mean difference = 0.31 m∙s⁻¹, MLS < MySp). Overall, the MLS is in agreement with the MySp app and is a reliable device for assessing sprint times, V_MAX, HZT P₀, and S_FV. Proportional bias should be considered for V_MAX when comparing the MLS to the MySp app.

The Viking press exercise is an upper-body strength and power movement with several potential benefits for athletes. The aim of this article is to describe proper exercise technique and introduce variations for the Viking press.

Photobiomodulation therapy (PBMT) can be applied to the whole body as compared to the application of using single hand-held devices that isolate a smaller muscle area. The purpose of this study was to examine the effects of an acute dose of whole-body PBMT pre- and post-high-intensity resistance training on creatine kinase (CK) and salivary interleukin-6 (IL-6) in a sample of trained males. Twelve males (31 ± 8.3 years, 177.2 ± 5.4 cm, and 86.0 ± 7.5 kg) were part of a randomized, counterbalanced, cross-over design, whereby each participant performed a high-intensity resistance training session that consisted of the bench press, chin-up, and repeated sprints on two separate occasions. Each participant was assigned to either the PBMT or control condition on two separate weeks, with a 10-days washout period between the weeks. Creatine kinase was measured at baseline, 24, 48, and 72 h post-exercise. Salivary IL-6 was measured at baseline, 60, 90, and 120 min. A paired t-test showed no significant difference (p = 0.669) in the area under the curve (AUC) for CK during the PBMT (191.7 ± 48.3) and control conditions (200.2 ± 68.0). A Wilcoxon signed-rank test also showed no significant median difference (p = 0.155) in the AUC for salivary IL-6 during the PBMT (Mdn = 347.7) and control conditions (Mdn = 305.8). An additional Wilcoxon signed-rank test for CK percentage change from 24 to 72 h showed the PBMT condition (Mdn = −45%) to have a −18% median difference as compared to the control condition (Mdn = −41%). As such, whole-body PBMT does not significantly reduce the activity of salivary IL-6 or CK concentration during the 24 to 72-h recovery post-high-intensity resistance training.

To determine the agreement between the Open Barbell (OB) and Tendo weightlifting analyzer (TWA) for measuring barbell velocity, eleven men (19.4 ± 1.0 y) performed one set of 2–3 repetitions at four sub-maximal percentage loads, [i.e., 30, 50, 70, and 90% one-repetition maximum (1RM)] in the back (BS) and front squat (FS) exercises. During each repetition, peak and mean barbell velocity were recorded by OB and TWA devices, and the average of the 2–3 repetitions was used for analyses. Although the repeated measures analysis of variance revealed significantly (p ≤ 0.005) greater peak and mean velocity scores from OB across all intensities, high intraclass correlation coefficients (ICC_2,K = 0.790–0.998), low standard error of measurement (SEM_2,K = 0.040–0.119 m·s⁻¹), and coefficients of variation (CV = 2–4%) suggested consistency between devices. Positive (r = 0.491–0.949) Pearson correlations between averages and differences (between devices) in peak velocity, as well as associated Bland-Altman plots, showed greater differences occurred as the velocity increased, particularly at low-moderate intensity loads. OB consistently provides greater barbell velocity scores compared to TWA, and the differences between devices were more apparent as the peak velocity increased with low-to-moderate loads. Strength coaches and athletes may find better agreement between devices if the mean velocity scores are only considered.

Background: Post-activation potentiation (PAP) is a neuromuscular phenomenon that has been shown to augment muscular force generating attributes as well as neural and sensory recruitment. While PAP has demonstrated to acutely enhance muscular performance during high-intensity activities, the effect of PAP on lumbopelvic kinematics under load remains unknown. Objectives: The purpose of this study was to examine the potential PAP effect of a hip abduction maximal voluntary isometric contraction (MVIC) on lumbar motion and power output during the barbell back squat. Methods: Nine resistance-trained men (22.9±2.3 y; 85.0±13.8 kg; 174.3±5.1 cm) performed a set of 5 repetitions of the barbell back squat using 80% one-repetition maximum with and without a hip abduction MVIC prior to performance. Experimental and control trials were randomized and counterbalanced among participants. MVIC was carried out via manual long-lever hip abduction. During the back squat exercise, lumbar motion analysis was performed using wireless motion-sensor technology, and power output was assessed via an accelerometer. Results: No significant differences were observed between trials for lumbar flexion range of motion (ROM) (p=0.32), lumbar flexion maximum deviation (p=0.32), lumbar lateral flexion ROM (p=0.81), lumbar lateral flexion maximum deviation (p=0.98), lumbar rotation maximum deviation (p=0.70), average peak power (p=0.98), or average mean power output (p=0.99) during the squat protocol. Conclusions: Implementation of a manual long-lever hip abduction MVIC prior to the back squat exercise did not significantly alter lumbar motion or augment power output in resistance trained males.