The Impact of an 8-Week Resisted Sprint Training Program on Ice Skating Performance in Male Youth Ice Hockey Players.

ABSTRACT: Dietze-Hermosa, MS, Montalvo, S, Gonzalez, MP, and Dorgo, S. The impact of an 8-week, resisted, sprint training program on ice skating performance in male youth ice hockey players. J Strength Cond Res 38(5): 957-965, 2024-The purposes of this randomized control study were to (a) compare the effects of an on-ice versus an overground resisted sprint training intervention and a control condition and (b) identify changes in ice skating kinematics and kinetics after training intervention participation. Twenty-four youth ice hockey players were randomly allocated into 3 groups: (a) on-ice resisted sprint training (on-ice RST); (b) overground resisted sprint training (overground RST); and (c) body weight resistance training (control). During the 8-week intervention, the 2 RST groups engaged in sled towing methods, whereas the control group engaged in a body weight resistance training program twice a week. A series of individual, repeated-measures analysis of variances with post hoc pairwise comparisons were conducted for variables of interest. An interaction effect was noted for ice skating s-cornering agility drill completion time ( p = 0.01; ηp2 = 0.36), ice skating 30-m top speed completion time ( p = 0.04; ηp2 = 0.27), step length ( p = 0.04; ηp2 = 0.26), and knee angle at touchdown ( p = 0.03; ηp2 = 0.30). The on-ice RST group displayed superior improvements across ice skating tests compared with the control group. Data show that on-ice RST has the greatest transfer effect to ice skating metrics; however, improvements in certain ice skating metrics can be observed with overground training also.

Effects of Different Stretching Modalities on the Antagonist and Agonist Muscles on Isokinetic Strength and Vertical Jump Performance in Young Men.

ABSTRACT: Montalvo, S, Gonzalez, MP, Dietze-Hermosa, MS, Martinez, A, Rodriguez, S, Gomez, M, Ibarra-Mejia, G, Tan, E, and Dorgo, S. Effects of different stretching modalities on the antagonist and agonist muscles on isokinetic strength and vertical jump performance in young men. J Strength Cond Res XX(X): 000-000, 2024-Exercise warm-up may include static or dynamic stretching, impacting performance differently. This study investigated the effects of various stretching protocols on isokinetic strength, muscular activity, and vertical jump performance. Sixteen subjects, divided evenly between trained and untrained groups, underwent 8 distinct stretching conditions in random order. Outcomes measured included isokinetic knee extension and flexion torque and power, muscular activity (vastus lateralis, vastus medialis, and biceps femoris), and jump performance (jump height and modified reactive strength index [RSImod]). Responses to the stretching conditions were analyzed using a mixed-methods approach. For isokinetic knee extension, dynamic stretching of both agonist and antagonist (DY-AG-ANT) and combined dynamic agonist with static antagonist stretching (DY-AG ST-ANT) produced significant improvements. Dynamic stretching of both agonist and antagonist increased peak torque by 12.72% and average torque by 30.80%, while DY-AG ST-ANT increased peak torque by 15.61% and average torque by 41.06%. Muscular activity also improved significantly; DY-AG ST-ANT increased EMG activity of the vastus lateralis by 29.43% and vastus medialis by 70.75%. Biceps femoris saw a 33.18% increase with DY-AG and a 22.15% increase with ST-AG. Countermovement jump height improved with DY-AG-ANT (12.6%) and static antagonist (ST-ANT) conditions (11.3%) ( p < 0.05). Dynamic stretching of both agonist and antagonist also enhanced average power knee extension by 32.41%, while ST-AG DY-ANT improved it by 31.09% ( p < 0.05). Dynamic stretching, especially when combined with static stretching, optimizes isokinetic strength, muscular activity, and jump height. Coaches should incorporate dynamic stretching, alone or with static antagonist stretching, to maximize performance.

Commercial Smart Watches and Heart Rate Monitors: A Concurrent Validity Analysis.

ABSTRACT: Montalvo, S, Martinez, A, Arias, S, Lozano, A, Gonzalez, MP, Dietze-Hermosa, MS, Boyea, BL, and Dorgo, S. Smartwatches and commercial heart rate monitors: a concurrent validity analysis. J Strength Cond Res 37(9): 1802-1808, 2023-The purpose of this study was to explore the concurrent validity of 2 commercial smartwatches (Apple Watch Series 6 and 7) against a clinical criterion device (12-lead electrocardiogram [ECG]) and a field criterion device (Polar H-10) during exercise. Twenty-four male collegiate football players and 20 recreationally active young adults (10 men and 10 women) were recruited and participated in a treadmill-based exercise session. The testing protocol included 3 minutes of standing still (resting), then walking at low intensity, jogging at a moderate intensity, running at a high intensity, and postexercise recovery. The intraclass correlation (ICC 2,k ), and Bland-Altman plot analyses showed a good validity of the Apple Watch Series 6 and Series 7 with increased error (bias) as jogging and running speed increased in the football and recreational athletes. The Apple Watch Series 6 and 7 are highly valid smartwatches at rest and different exercise intensities, with validity decreasing with increased running speed. Strength and conditioning professionals and athletes can confidently use the Apple Watch Series 6 and 7 when tracking heart rate; however, caution must be taken when running at moderate or higher speeds. The Polar H-10 can surrogate a clinical ECG for practical applications.

Common Vertical Jump and Reactive Strength Index Measuring Devices: A Validity and Reliability Analysis.

ABSTRACT: Montalvo, S, Gonzalez, MP, Dietze-Hermosa, M, Eggleston, JD, and Dorgo, S. Common vertical jump and reactive strength index measuring devices: A validity and reliability analysis. J Strength Cond Res 35(5): 1234-1243, 2021-Several field-test devices exist to assess vertical jump, but they either lack proper validation or have been validated for the countermovement jump (CMJ) only. This study aimed to quantify the validity and reliability of metrics, including jump height and the calculated reactive strength index (RSI), obtained using the flight-time method from 4 different assessment devices with 3 different vertical jump modalities in comparison to a force platform (criterion assessment). The Optojump, Push-Band 2.0, MyJump2 mobile application, and What'sMyVert mobile application were used synchronously and together with the force platforms. Thirty subjects (17 males and 13 females; age ± SD: 23.37 ± 1.87 years) performed 5 repetitions of CMJ, squat jump (SQJ), and drop jump (DJ) with a standardized 90° knee flexion for all jumps. Relative reliability was determined by intraclass correlation (ICC) and absolute reliability by coefficient of variation (CV) analyses. Excellent reliability was considered as ICC > 0.9 and CV < 10%. Validity was obtained through an ordinary least products regression, ICC, and CV. Significance was set at p < 0.05. Reliability was excellent on jump height for the CMJ (ICC ≥ 0.98; CV ≤ 8.14%) for all instruments. With the exception of the Optojump, all instruments also had excellent reliability for the SQJ (ICC ≥ 0.98; CV ≤ 6.62) and DJ (ICC ≥ 0.94; CV ≤ 8.19). For the RSI metric, all instruments had excellent relative reliability (ICC ≥ 0.92), but none had excellent absolute reliability (CV ≥ 12.5%). The MyJump2 and What'sMyVert apps showed excellent validity on all jump modalities and RSI. The Optojump and Push-Band 2.0 devices both showed system and proportional bias for several jump modalities and RSI. Overall, both mobile applications may provide coaches with a cost-effective and reliable measurement of various vertical jumps.

Effects of Augmented Eccentric Load Bench Press Training on One Repetition Maximum Performance and Electromyographic Activity in Trained Powerlifters.

ABSTRACT: Montalvo, S, Gruber, LD, Gonzalez, MP, Dietze-Hermosa, MS, and Dorgo, S. Effects of augmented eccentric load bench press training on one repetition maximum performance and electromyographic activity in trained powerlifters. J Strength Cond Res 35(6): 1512-1519, 2021-Augmented eccentric load (AEL) training has been shown to elicit greater lower-body muscular strength increases and faster performance improvements compared with traditional strength training. However, it is unknown whether AEL training could provide similar improvements in upper-body muscular strength. Therefore, this study investigated the effects of a 4-week AEL training program on bench press one repetition maximum (1RM) strength, bar kinetics and kinematics, and surface electromyography (EMG) activity. Eight competitive powerlifters completed 5 training sessions consisting of 7 sets of a single repetition with up to 5 minutes rest between sets. Each session was completed at a predetermined AEL percentage consisting of 90% 1RM for concentric and supramaximal loads ranging from 105 to 125% 1RM during the eccentric phase with the use of eccentric hooks. After 4 weeks of AEL training, 1RM performance significantly increased from pretest to posttest (116.62 ± 27.48-124.28 ± 26.96 kg, p = 0.001). In addition, EMG amplitude of the pectoralis major decreased during the 125% AEL session to 59.86 ± 15.36% of pretest 1RM EMG values (p = 0.049, effect sizes [ESs] = 0.69). Furthermore, peak power of 1RM increased by 36.67% from pretest to posttest (p = 0.036, ES = 0.58). These study findings suggest that incorporating AEL bench press training into a 4-week training cycle may be a novel strategy to improve 1RM performance in competitive powerlifters in a short period.

Comparative kinematic analysis of high-speed treadmill vs. overground sprinting across athletic levels and sex.

BACKGROUND: This investigation aimed to dissect the kinematic differences in sprinting between high-speed treadmill and overground conditions, examining how these variations are influenced by the athlete's training status and biological sex. METHODS: A total of 40 participants, 20 NCAA Division 1 sprinters and 20 recreational runners, performed a series of maximal sprints on a high-speed treadmill and on a standardized competition overground track. Sprinting kinematic variables such as stride length, stride frequency, contact time, and flight time were collected via photoelectric sensors. Maximal sprinting kinematics were analyzed by linear mixed-effects models, considering the impacts of sprinting environment (treadmill vs. overground), training level, and sex, with leg length as fixed factors and individual athletes as random effects. Statistical significance was set at a significance level of 0.05. RESULTS: The statistical analysis revealed that high-speed treadmill sprinting significantly affects all measured kinematic variables, leading to increased stride frequency and contact time. Elite sprinters demonstrated enhanced kinematic efficiency over recreational runners, characterized by increased stride length and frequency and reduced contact time. Sex-based kinematic distinctions also emerged, with male athletes exhibiting superior stride length and frequency compared to female athletes. Leg length significantly influenced stride frequency, and an interaction effect was observed for flight time between sprint type and athletic group. CONCLUSIONS: These findings elucidate the distinct biomechanical profiles across sprinting modalities and athlete demographics, emphasizing the need for sprint training customization. This study's insights offer a valuable reference for coaches and athletes to refine training and performance assessment in varied sprinting environments.

A Comparison of Morphological, Jump, and Sprint Kinematic Asymmetries in Division I Track and Field Athletes.

Inter-limb asymmetries are the difference in performance in one limb with respect to the other. Running events in track and field are considered symmetrical while jumping and throwing events are considered asymmetrical. It is unknown if competing in these different events result in differences in inter-limb asymmetries, thus, this study compared the magnitude of jump, sprint, and morphological asymmetries in track and field athletes who compete in symmetrical and asymmetrical events. Forty-six Division I track and field athletes performed a series of vertical jumps (VJ) and broad jumps (BJ) with force platforms measuring peak force of each limb, and 30-meter fly sprints with kinematics (step length (SL), flight time (FT), and contact time (CT)) recorded during the sprints. Additionally, thirty-eight of these subjects underwent body composition analysis via dual x-ray absorptiometry to determine morphological asymmetries. Asymmetries were calculated using the symmetry index and the asymmetry measures were compared between sprinters, distance runners, throwers, and jumpers utilizing a one-way analysis of variance or Kruskal-Wallis tests with post-hoc comparisons as necessary. There were no differences in VJ, BJ, and sprint kinematic asymmetries found between groups but there were differences in leg fat mass asymmetries (H(3)=8.259, p=0.041, eta2= 0.101) as well as arm lean mass (H(3)=9.404, p=0.024, eta2=0.152), fat mass (H(3)=17.822, p<0.001, eta2=0.353), and tissue mass (H(3)=11.632, p=0.009, eta2=0.206) asymmetry measures. While morphological asymmetry differences may be present in athletes competing in different events, there does not appear to be differences in asymmetries during the VJ, BJ, and 30-m fly sprint.

Effects of manual resistance versus weight resistance training on body composition and strength in young adults after a 14-week intervention.

Manual Resistance Training (MRT) is an alternative training modality where the external resistance is provided by a spotter. PURPOSE: The purpose of this study was to observe changes in body composition and muscular fitness after a 14-week MRT intervention compared to changes elicited by a Weight Resistance Training (WRT) intervention. METHODS: Eighty-four young adults were randomly assigned to either the MRT (n = 53, height 170.1 ± 8.1 cm, body mass 73.9 ± 16.0 kg, and body fat 24.6 ± 8.7%) or WRT (n = 31, mean ± SD: height 169.6 ± 10.1 cm, body mass 75.0 ± 17.4 kg, and body fat 24.7 ± 8.5%) group. Body composition was assessed by Dual-energy X-ray Absorptiometry (DEXA), muscular strength and muscular endurance were tested before and after the intervention. RESULTS: Findings indicated that trunk, arm, leg, and total lean mass increased in both groups after the intervention (p < 0.05). Moreover, total fat mass significantly decreased compared to baseline in both groups (p < 0.05). However, no statistically significant changes were observed in Bone Mineral Density and Bone Mineral Content in response to the intervention. Both MRT and WRT programs were successful at significantly increasing muscular strength and endurance (p < 0.05). CONCLUSION: The changes in body composition after a 14-week MRT program were similar to those of the WRT intervention. Hence, an MRT program may be effectively used to increase lean mass and decrease fat mass.

Physical fitness in older adults: Is there a relationship with the modified Functional Movement Screen™?

INTRODUCTION: The modified Functional Movement Screen™ (mFMS) has been used to screen for mobility, stability, motor control, and balance in older adults, yet, its relationship to measures of physical fitness is not fully understood. The purpose of this study was to determine the association between mFMS scores and measures of physical fitness in older adults. A secondary aim was to determine physical fitness differences depending on mFMS Lower Body Motor Control Screen scores. METHODS: One hundred and eight older adults completed this cross-sectional study. Measurements of physical fitness included: Handgrip Strength (HG), Back-Leg Strength Dynamometer (BLS), 8 foot Up and Go (8UG), Vertical Jump (VJ), Medicine Ball Throw (MBT), Chair Stand (CST), Arm Curl (AC), and 6-Minute Walk test (6 MW). The mFMS consisted of four screens: Shoulder Mobility Screen (SMS), Deep Squat (DS), Active Straight Leg Raise (ASLR), and a Lower Body Motor Control Screen (LB-MCS). Spearman's R correlations determined associations between physical fitness tests and mFMS scores (DS, SMS, ASLR). Independent t-tests or Mann Whitney U tests determined whether individuals who passed the LB-MCS displayed higher physical fitness scores. RESULTS: The DS was significantly correlated with all fitness measures (p < 0.05). Higher DS scores were associated with better HG (r = 0.31), BLS (r = 0.49), VJ height (r = 0.54), MBT (r = 0.41), CST (r = 0.57), AC (r = 0.30), 6 MW (r = 0.50), and 8UG (r = -0.61) performance. Individuals who passed the LB-MCS displayed superior BLS, 8UG test, and 6 MW test performance (p < 0.05). DISCUSSION & CONCLUSION: Higher DS scores are associated with higher physical fitness scores. Individuals who passed the LB-MCS displayed better physical fitness scores. Practitioners may desire to use the mFMS to measure physical fitness in older adults.

Association and Predictive Ability of Jump Performance with Sprint Profile of Collegiate Track and Field Athletes.

This study examined the relationship between broad jump (BJ), countermovement jump (CMJ) and light load countermovement jump (LL-CMJ) performance and sprint performance and Sprint Profile measures in athletes. Additionally, this study aimed to determine the predictive ability of jump measures on Sprint Profile components. Twenty-five athletes performed BJ, CMJ, LL-CMJ, 30-metre acceleration and 30-metre maximal speed fly-by sprints. Results revealed moderate to very large correlations between BJ, CMJ and LL-CMJ performance with acceleration sprint completion times (r = -0.423 to -0.807; p < 0.05), fly-by sprint completion times (r = -0.452 to -0.838; p < 0.05) and maximal sprint speed (r = 0.424 to 0.794; p < 0.05). Additionally, associations were observed with multiple jumping measures and components of the Sprint Profile (r = 0.431 to 0.777; p < 0.05) during acceleration sprints. Furthermore, the BJ distance was the best predictor of Sprint Profile components during acceleration sprints (R2 = 0.57-0.76; p < 0.01) and maximal speed fly-by sprints (R2 = 0.775; p < 0.001). The forces and the manner of force application during the BJ to propel the athlete forwards and upwards are similar to those necessary to exhibit superior sprint performance. This may be due to the rapid generation of forces and orientation of force application during both movements.

Intra-abdominal Pressure and Pelvic Floor Health: Should We Be Thinking About This Relationship Differently?

OBJECTIVES: Intra-abdominal pressure (IAP) increases during physical activity. Activities with high IAP are often restricted for women because of potential pelvic floor overloading. Researchers categorize high IAP activities using absolute values (in centimeters of water). Although essential for descriptive purposes, absolute IAP may not be ideal for individualized exercise recommendations. For oxygen consumption, a well-established measure of fitness, exercise scientists use a percentage of the maximal value observed during exercise to create relative exercise intensity prescriptions for an individual. Relative exercise intensity correlates inversely to the maximal value observed. We explore whether this approach and response pattern extend to IAP observed during exercise. METHODS: Fifty-five women completed 16 exercises while wearing a vaginal sensor to measure IAP. The highest mean IAP occurred during seated Valsalva/strain (IAPSTRAIN). We calculated relative IAP (in percent) for each participant by dividing the maximal IAP during each exercise by IAPSTRAIN. We examined relationships between relative IAP and IAPSTRAIN for each activity using Pearson r correlations. RESULTS: Mean age was 30.4 ± 9.4 years, and body mass index was 22.4 ± 2.6 kg/m. For most women, IAP was greater during strain than during exercises. Relative IAPs negatively correlated with IAPSTRAIN. Excluding one exercise because of small sample sizes, r for all others ranged from -0.35 to -0.80, all statistically significant. CONCLUSIONS: The relative IAP responses to many exercises exhibit an inverse relationship to the highest IAP values during strain, consistent with other variables measured during exercise. Relative IAP may provide an alternative to absolute IAP in understanding IAP's effect on pelvic floor health.