Strength Training and Performance Enhancement in Athletes, 2nd Edition

Background: The aim of the study was to investigate the effect of six weeks of training with wearable resistance attached to the forearm on throwing kinematics, strength, and velocity in experienced female handball players. Methods: Twenty-five female handball players (mean age: 24.7 ± 3.8 y, mass: 72.1 ± 17.6 kg, height: 1.69 ± 0.06 m, and training experience: 14.3 ± 4.9 y) participated and were divided into an experimental group (n = 14) or a control group (n = 11). Both groups participated in the same handball sessions, but the experimental group trained with wearable resistance attached to the forearm during the training sessions. Before and after a training period of six weeks, throwing velocity, strength, and kinematics were tested. Results: The throwing velocity was significantly increased in the experimental group but not in the control group (p = 0.006). Only a few significant kinematic changes were observed, mostly around ball release, in which both groups had increased elbow flexion. The experimental group had a larger shoulder flexion at ball release and a more flexed wrist (p ≤ 0.04). Meanwhile, the control group had a lower shoulder abduction after the training period (p ≤ 0.023). No significant effects were found in the maximal angular velocities, timing of joint angles, angular velocities and in the strength test (p > 0.075). Conclusions: Based on the findings in this present study, it was concluded that training with wearable resistance attached to the forearm increases throwing velocity during the competition season compared to normal throwing training, which was probably caused by the changes in maximal elbow angle and extension velocity and the more flexed wrist at ball release. Full article

Background: The forward lunge is a closed-chain weight-bearing multi-joint exercise simulating the activities of daily living, such as walking or stair climbing, which mainly activates hip, knee, and ankle musculature and is also used by athletes and other individuals to train lower-extremity musculature. Objectives: The purpose of this study is to compare lower-extremity muscle recruitment patterns between stride and step length variations in forward lunges. Methods: Twenty participants had a mean (±SD) age, mass, and height of 26 ± 6 y, 79 ± 8 kg, and 176 ± 7 cm, respectively, for males, and 27 ± 4 y, 62 ± 6 kg, and 161 ± 7 cm, respectively, for females. All participants used their 12-repetition maximum weight while performing a short step and long step forward lunge with a stride (striding forward and pushing back to the starting position) and without a stride (lunging up and down with feet stationary). During each lunge variation, surface electromyography (EMG) data were collected from the quadriceps, hamstrings, gastrocnemius, hip adductors, gluteus maximus, and gluteus medius muscles, and then normalized as a percent of each muscle’s maximum voluntary isometric contraction. A repeated measures two-way analysis of variance was employed (p < 0.01), with step length and stride comprising the two factors. Results: The following had no significant interactions: (1) quadriceps, hamstrings, gastrocnemius, hip adductor, and gluteus maximus EMG activities were significantly greater in lunges with a long step compared to lunges with a short step; and (2) gluteus maximus and gluteus medius EMG activities were significantly greater in lunges with a stride compared to lunges without a stride. The following had significant interactions: (1) gluteus medius EMG activities were significantly greater in lunges with a long step with and without a stride compared to lunges with a short step with and without a stride; (2) quadriceps EMG activities were generally significantly greater in lunges with long and short steps with a stride compared to lunges with long and short steps without a stride, in lunges with a long step with a stride compared to lunges with a short step with a stride, and in lunges with a short step without a stride compared to lunges with a long step without a stride; (3) hamstring and hip adductor EMG activities were significantly greater in lunges with a long step with a stride compared to lunges with a long step without a stride, and in lunges with a long step with and without a stride compared to lunges with a short step with and without a stride; and (4) gastrocnemius EMG activities were significantly greater in lunges with a long step with and without a stride compared to lunges with a short step with and without a stride. Conclusions: Lower-extremity muscle activity is generally greater in forward lunges with a long step compared to a short step, and greater in lunges with a stride compared to without a stride. During the externally loaded forward lunge, high to very high muscle activity occurs in the quadriceps, gluteus maximus, and gluteus medius, thus enhancing muscle hypertrophy and strength in these muscles, while moderate muscle activity occurs in the hamstrings, gastrocnemius, and adductor longus. Full article

Background: The Keiser 10-rep leg press test protocol employs short inter-repetition rest intervals (2–38 s), raising concerns as to whether athletes perform optimally. Objectives: The aim of this study was to compare the results of the standard Keiser protocol with an identical protocol modified to include a significantly longer inter-repetition rest intervals and to evaluate whether these effects differed between men and women. Methods: A total of 30 athletes (age 17.1 ± 0.9 years, height 177.8 ± 8.8 cm, and body mass 71.9 ± 11.3 kg) performed three separate tests (total of ~900 repetitions) in a Keiser A420 leg press machine, separated by 4 to 8 days. Test day 1 included a 1RM test followed by a 10-repetition force–velocity test with a standard rest intervals. Test days 2 and 3 involved the same test, with either standard short rest intervals or fixed 3 min inter-repetition rest intervals. Results: Increasing inter-repetition rest intervals significantly improved V₀ and P_max for men and V₀ and FV_slope for women. The benefits of longer rest were notably more pronounced in men, particularly at light to moderate loads, where standard Keiser rest intervals are short (2–9 s). However, extending rest intervals beyond approximately 30 s, as applied at higher loads, provided no additional advantages. Conclusions: Longer rest intervals improved force–velocity metrics more in men than women, with the effect being most pronounced at light to moderate loads where standard protocols utilize short rest intervals (2–9 s). These findings suggest that women recover faster than men under these conditions. However, extending rest beyond 30 s at higher loads provides no additional benefits and is counterproductive at maximal loads. Full article

Objectives: The purpose of the present study was to evaluate the level of physical capacities of Italian American Football (AF) players and compare their performances with published data of American college players. A secondary aim was to assess whether the performance of Italian players in the NFL Combine tests has improved over time compared to previously tested players of similar competitive level. A total of 41 Italian AF players (age 28.1 ± 4.7 y, stature 181.1 ± 5.9 cm, body mass 98.3 ± 17.8 kg) competing in the 2020/2021 Division I Championship, participated in this study and performed the NFL Combine test battery. Methods: The NFL Combine test battery includes the 40-yard dash, the 20-yard shuttle, the 3-cone drill tests, the broad jump test, the vertical jump test, and the maximum number of repetitions at bench press with a 100 kg load. Players were divided into three groups based on their playing position: skill players (SP = 14), big skill players (BSP = 9), or linemen (LM = 13). In addition, players’ performance scores were normalized to their stature and body weight. Results: Italian players showed lower performances in all the six tests compared to American college players. Significant differences were observed between player positions. Normalized performances were significantly lower in Italian compared to American players. Conclusions: Despite an improving trend in the NFL Combine tests being registered in Italian AF players, a relevant gap still exists compared to their US counterparts. Full article

Background: Assessments of muscle strength help prescribe and monitor training loads in cyclists (e.g., triathletes). Some methods include repetition maximum, joint isokinetic tests, and indirect estimates. However, their specificity for cycling’s dynamic force application and competitive cadences is lacking. This study aims to determine the influence of the cycling isokinetic peak force (cIPF) at different cadences on aerobic performance-related variables in trained triathletes. Methods: Eleven trained male athletes (33 ± 9.8 years, 173.1 ± 5.0 cm height, 73.9 ± 6.8 kg body mass, and ≥5 years of triathlon experience) were recruited. Maximal oxygen consumption (VO₂ max), ventilatory thresholds (i.e., VT1 and VT2), and cIPF were assessed. cIPF testing involved 10 s sprints at varied cadences with 4 min rest intervals. Pedaling cadences were set at low (60 rpm), moderate (80 and 100 rpm), and high (120 and 140 rpm) cadences. A regression model approach identified cIPF related to aerobic performance. Results: IPF at 80 and 120 rpm explained 49% of the variability in power output at VT1, 55% of the variability in power output at VT2, 65% of the variability in power output at maximal aerobic power (MAP), and 39% of the variability in VO₂ max. The cycling economy was not explained by cIPF. Conclusions: This study highlights the significance of cIPF, particularly at moderate to high cadences, as a determinant of aerobic-related variables in trained triathletes. Cycling cIPF should be tested to understand an athlete’s profile during crank cycling, informing better practice for training specificity and ultimately supporting athletes in achieving optimal performance outcomes in competitive cycling events. Full article

Background/Objectives: The aim of this study was to investigate the effects of a six-week integrated resisted sprint training (IRST) program on sprint performance and vertical jump height in a sample of U-14 male football players. This study also explored the potential benefits of incorporating variable resistive loads during pre-peak height velocity (pre-PHV) developmental stages, a period often overlooked in the training of young athletes. The IRST program alternated between heavy and light resistive sled loads to enhance sprint and jump capabilities, which are critical components of athletic performance in football. Methods: Nineteen healthy male football players (age: 13 ± 0.63 years) were divided into an experimental group (E, n = 10) and a control group (C, n = 9). The experimental group followed the IRST protocol, involving sled sprints with varying resistive loads (10–115% of the body mass) over specific distances, while the control group engaged in traditional unresisted sprint training. The sprint performance was assessed using 30 m sprint times, and the vertical jump height was measured using countermovement jump (CMJ) data collected via a force platform. Anthropometric measures and peak height velocity (aPHV) estimates were also recorded pre- and post-intervention. Results: The experimental group demonstrated significant improvements in 30 m sprint times (mean difference: −0.29 s; p < 0.01). Additionally, CMJ data revealed a positive trend in the take-off velocity and maximum concentric power, with an increase in jump height (mean difference: +0.44 cm). These results suggest enhanced sprint and explosive power capabilities following the IRST intervention. Conclusions: The findings suggest that the IRST program is an effective training method for enhancing sprint performance and maintaining jump capabilities in young football players. This approach highlights the importance of integrating variable resistance training in pre-PHV athletes to promote athletic development while ensuring safety and effectiveness. Full article

Background: Balance tasks are critical for performance in acrobatic gymnastics, where athletes often train and compete in mixed-age groups with varying maturational stages. To improve individualized training, in this cross-sectional study, the relationship was examined between strength capacity and balance task performance in female gymnasts at two maturational stages based on peak height velocity (PHV). Methods: Circa-PHV (n = 17, 11.92 ± 1.7 years) and post-PHV (n = 17, 16.47 ± 1.8 years) participants performed static balance tasks (standing on blocks, tandem stance, headstand) while center of pressure (CoP) excursion was recorded, and a proactive balance task (time to stabilization after landing, TTS). Strength assessments included isometric mid-thigh pull, handgrip, countermovement jump (CMJ), and push-up tests. Results: Correlational, regression, and inter-group analyses highlighted differences in strength–balance relationships across groups. Maximal isometric strength and CMJ power were the strongest predictors of static standing balance, with greater predictive strength in the circa-PHV group, underscoring the role of maturation in strength–balance interactions. The results also revealed that strength parameters influenced balance differently depending on the task, suggesting that specific balance types (static–proactive) and tasks (standing–inverted) require distinct strength capacities. Conclusions: Strength’s influence on balance varies by maturational stage, emphasizing the need for tailored training programs to enhance balance and optimize performance in young gymnasts. Full article

Blood flow restriction (BFR) is a popular resistance exercise technique purported to increase metabolic stress and augment training adaptations over time. However, short-term use may lead to acute neuromuscular fatigue and higher exertion ratings. Objective: The purpose of the current study was to examine acute physiological responses to low-load resistance exercise utilizing BFR compared to higher-load, non-BFR resistance exercise. Methods: Recreationally trained males (n = 6) and females (n = 7) (mean ± standard deviation, age: 20 ± 1 yrs.; height: 172 ± 8 cm; weight: 73 ± 11 kg; BMI: 24.4 ± 2.2 kg·m⁻²; training experience: 4 ± 2 yrs.) had limb occlusion pressure determined (50%; right leg: 118 ± 11 mmHg; left leg: 121 ± 13 mmHg) using an automated, self-inflating cuff system during baseline testing. In subsequent sessions, using a randomized, cross-over design, participants completed one of two experimental conditions: (1) Low-load + BFR and (2) High load + non-BFR. In both conditions, participants completed one set of back squats at either 30% (BFR) or 60% (non-BFR) of an estimated 1RM for a max of 30 repetitions, followed by three additional sets with the same loads and a target of 15 repetitions per set. Blood lactate and countermovement jump (CMJ) height were measured pre- and post-back squat. Ratings of perceived exertion (RPE) were assessed following each set. Results: When collapsed across all sets, participants completed significantly more total repetitions in the BFR condition compared to non-BFR (75.0 ± 0.0 vs. 68.23 ± 9.27 reps; p = 0.015; ES: 1.03), but a lower training load volume (2380 ± 728 vs. 4756 ± 1538 kg; p < 0.001; ES: 1.97). There was a significant time-by-condition interaction (p < 0.001), with a greater increase in blood lactate occurring from baseline to post-back squat in the non-BFR condition (11.61 mmol/L, 95%CI: 9.93, 13.28 mmol/L) compared to BFR (5.98 mmol/L, 95%CI: 4.30, 7.65 mmol/L). There was another significant time-by-condition interaction (p = 0.043), with a greater reduction in CMJ occurring in the non-BFR condition (−6.01, 95%CI: −9.14, −2.88 cm; p < 0.001) compared to BFR (−1.50, 95%CI: −1.50, 4.51 cm; p = 0.312). Conclusions: Utilizing a low-load BFR protocol may allow for a higher training volume, yet lower metabolic stress and reduce neuromuscular fatigue compared to lifting at a higher load without the use of BFR. Full article

Background/Objectives: Both Sides Utilized it is one of the most employed global instability devices (GID), but it is difficult to progress and select a particular foot structure. In this sense, the Blackboard has been created as selective instability device (SID). The aim of this study is to compare the effects of both devices on balance and ankle stability. Methods: The study was designed as a randomized controlled clinical trial. Twenty healthy amateur soccer players were divided into two groups: GID and SID. Both performed balance training (4-weeks, 3 days/week). Ankle balance and stability were assessed. Paired t-tests were used to analyze the pre-, post-, and between-groups differences. Results: No differences were found between the groups. Significant intra-group changes were found in both groups for posterolateral balance and summation. Moreover, posteromedial balance increased in the GID group. No changes were found in ankle stability results. Conclusions: A balance intervention using GID or SID is effective in improving general and posterolateral balance. Moreover, the GID intervention improved posteromedial balance. Full article

Background: Muscle fatigue is inevitable during resistance exercises, making its monitoring essential for maintaining athletic performance and reducing the risk of injury. Ratings of perceived exertion (RPE) and velocity loss have been reported as reliable indicators of muscle fatigue during explosive resistance exercises. However, their validity has been assessed only indirectly. This study aimed to directly examine the validity of RPE and velocity loss as markers of muscle fatigue during explosive back squat (BS) exercises. Methods: Seventeen trained men performed three BS tasks with varying volumes (low, medium, high) at 65% of their one-repetition maximum. RPE, spectral fatigue index (SFI), and velocity loss were measured throughout the tasks. Results: Significant effects were observed across conditions for overall RPE (p < 0.001) and velocity loss (p < 0.001), while no significant effect was found for SFI. RPE and SFI increased significantly as the tasks progressed (p < 0.001), while velocity did not significantly decrease. Significant but weak correlations were found between RPE and SFI (r = 0.325, p < 0.001) and between velocity loss and SFI (r = 0.224, p < 0.001). Conclusions: These findings suggest that RPE and muscle fatigue levels increase correspondingly, indicating that RPE could serve as a practical, indirect fatigue marker for explosive BS exercises. However, velocity loss may not fully reflect muscle fatigue during lower-body explosive training and should not be used as the sole indicator. Additionally, caution is warranted when applying velocity-related parameters as indirect physiological markers for resistance exercises. The significant but weak correlations between RPE, velocity loss, and SFI suggest that assessing muscle fatigue in lower-body exercises remains challenging. Full article

Objectives: This study aimed to assess the impact of a 20-week resistance training program on force–velocity (F-V) parameters using an isokinetic two-point method and comparing one-repetition maximum (1-RM) methods in novice lifters. Methods: Previously untrained individuals completed a supervised, three-session weekly resistance training program involving concentric, eccentric, and isometric phases, repeated every 2 to 4 weeks. Isokinetic dynamometry measured the strength of elbow flexors/extensors at 60°/s and 150°/s, and knee flexors/extensors at 60°/s and 240°/s at Baseline, 3 months, and 5 months. F-V parameters, including maximal theoretical force (F0) and the F-V slope, were calculated. Participants also performed 1-RM tests for the upper and lower limbs. Repeated measures ANOVA with effect size (η² > 0.14 as large) was used to analyze changes in F-V parameters and repeated measures correlation was used to test their association with 1-RM outcomes. Results: Eighteen male participants (22.0 ± 3.4 years) were analyzed. F0 significantly increased for all muscle groups (η² = 0.423 to 0.883) except elbow flexors. F-V slope significantly decreased (steeper) for knee extensors and flexors (η² = 0.348 to 0.695). Knee extensors showed greater F0 gains and steeper F-V slopes than flexors (η² = 0.398 to 0.686). F0 gains were associated with 1-RM changes (r = 0.38 to 0.83), while F-V slope changes correlated only with lower limb 1-RM (r = −0.37 to −0.68). Conclusions: The 20-week resistance training program significantly increased F0 and shifted the F-V profile towards a more “force-oriented” state in knee muscles. These changes correlated with improved 1-RM performance. Future studies should include longer follow-ups and control groups. Full article