Atle Hole Saeterbakken

Background: Plyometric-jump training (PJT) has been recommended as an effective resistance training modality for enhancing vertical jump and lower limb muscle power in young athletes. While unstable surfaces are popular means to address progression and specificity, an alternative approach for applying instability during jumping is the inclusion of unstable loads. The purpose of this study was to compare the effects of unstable load PJT (UL-PJT) to PJT without unstable load (S-PJT) on physical fitness (i.e. jump performance, muscle strength, balance) of young volleyball players. Methods: Thirty-seven trained male volleyball players aged 16.8 ± 1.1 years were randomly assigned to UL-PJT, S-PJT, and active controls (CON). For 4 weeks (3 sessions/week), UL-PJT group performed jump exercises with external unstable loads (~ 10% body weight), while S-PJT comprised jump exercises without additional loads. Testing included assessment of jump-and-reach (J&R) height, drop jump (DJ) height, maximal isokinetic knee flexion/extension strength (e.g., peak isokinetic torque [PIT], time to PIT [TTP]), static balance (i.e., overall, anterior-posterior, and medial-lateral stability index). Results: Large group×time interaction effects ( p ≤ 0.048; 0.88 ≤ effect size (ES) ≤ 1.76) were noted for J&R height, knee extension TTP, and static balance. Post-hoc analyses revealed that overall stability index and J&R height improved after both UL-PJT and S-PJT. Moreover, both training programs induced specific improvements in anterior-posterior (S-PJT) and medial-lateral stability indices (UL-PJT). However, only UL-PJT improved knee extensor TTP. Conclusions: The present study demonstrated that 4 weeks of UL-PJT and S-PJT were equally effective for enhancing J&R and balance performance (i.e., overall stability index) with limited superior effects of UL-PJT over S-PJT (i.e., knee extensor TTP) in trained young volleyball players. Using unstable loads during PJT guarantees training stimulus variety with no disadvantage compared with S-PJT. Trial registration: Iranian Registry of Clinical Trials IRCT20250905067129N1 (2025-09-15, retrospectively registered).

Background: Both unilateral and asymmetric loading have been used to increase training specificity and create over-load in a target limb to reduce inter-limb asymmetries. The aim of the study was to compare the effects of conducting either unilateral- or asymmetric-loaded resistance training with traditional bilateral resistance training on maximal dynamic and isometric strength in untrained women. Methods: Thirty-four women not conducting regular resistance training were randomized into unilateral (UNI), bilateral (BIL) or asymmetric (ASY) upper-body resistance training (2–3·wk⁻¹, 10 wk, 24 sessions in total). UNI conducted all exercises unilaterally (one arm at a time), BIL conducted all exercises bilaterally (both arms), and ASY added 10% of the total load to the non-dominant side. Maximal strength was tested in chest press, seated row (1-RM and MVC in both), and pallof press (only MVC). Results: At post-test, BIL demonstrated greater bilateral 1 RM strength than ASY (p = 0.017, d = 1.25) in chest press, while UNI demonstrated greater 1 RM strength in the dominant side than ASY (p = 0.006, d = 1.45). For the other strength tests, no differences were found between groups in chest press (p = 0.068–0.481), seated row (p = 0.091–0.591) or MVC peak force for both chest press and seated row (p > 0.05). All groups demonstrated pre–post improvements for all measurements in chest press (p < 0.05) and seated row (p < 0.05), but only ASY demonstrated improvements in pallof press on the non-dominant side. Conclusions: Compared to traditional bilateral training, unilateral resistance training did not result in similar effects on dynamic or isometric strength. Asymmetric resistance training demonstrated a lower change in chest press strength on the bilateral and dominant sides compared to the other groups.

The modality of resistance training (e.g., plyometric training [PLYO], traditional resistance training [TRT]) can specifically affect gains in muscle strength and power measures in soccer players. Further, effects of resistance training modality on neuromuscular performance measures (e.g., electromechanical delay [EMD]) are inconsistent in non-athletes. To examine the effects of PLYO, TRT, and combined PLYO and TRT (i.e., complex training [CT]) on muscle strength, power, and EMD in highly trained male soccer players (age: 21.7 ± 1.6 years). Participants were randomly assigned to eight weeks of CT (n = 30), PLYO (n = 28), and TRT (n = 26) in addition to their regular soccer training, or soccer training control condition (n = 29). Pre- and post-measurements comprised tests for maximal eccentric knee flexor and concentric knee extensor peak torque (PT), their functional ratio (FUNC-H/Q), and the corresponding EMD of the knee flexors at three angular velocities (60, 180, and 300°/s). Results showed a significant main effect of group for concentric and eccentric PT (p<.001, 1.67 ≤ d ≤ 3.17). Concentric and eccentric PT were larger for CT, PLYO, and TRT groups compared to control group (CG) with the greatest effects for CT across all angular velocities (p<.001, 0.95 ≤ d ≤ 3.57). Additionally, a significant group effect was identified for FUNC-H/Q at 300°/s (p=.002, d = 0.83) with lower ratios in PLYO and TRT groups but not CT compared with CG (p<.001, -0.94 ≤ d≤-0.83). Further, significant and large-sized group effects for EMD were found at 60, 180, and 300°/s (p<.001, 0.96 ≤ d ≤ 2.89). Post-hoc test showed lower EMD values in CT compared with PLYO, TRT, and CG (p<.001, -2.88 ≤ d≤-0.87). Moreover, EMD was lower in PLYO and TRT compared with CG at 60 and 300°/s (p<.001, -1.84 ≤ d≤-1.10). Complex training, PT, and TRT were effective training modalities in improving neuromuscular performance (i.e., maximal eccentric knee flexor/concentric knee extensor PT, knee flexor EMD) in highly trained soccer players. More specifically, CT appears to be superior in maintaining higher FUNC-H/Q values compared with PLYO and TRT. This study does not report results related to healthcare interventions using human participants and therefore it was not prospectively registered on a clinical trial registry.

Objectives: The barbell back squat is one of the most frequently used exercises to improve lower-body strength and power. The aim of this study was to examine the impact of relative strength on the kinematics in the barbell back squat to a 90-degree angle. Methods: Forty-six recreationally trained men completed five familiarization sessions over three weeks to ensure proper lifting technique. The participants were tested in a ten-repetition maximum (10 RM), during which barbell velocity, acceleration, vertical displacement, and the time of the pre-sticking, sticking, and post-sticking regions were measured. The participants were then categorized into two groups: (1) the above-median group or (2) the below-median group, to examine whether kinematics were affected by relative strength (10 RM load/body weight). Results: The below-median group had a relative strength of 1.37, whereas the above-median group had a relative strength of 1.76. There was a 5.86% non-statistical difference (p = 0.052) in vertical barbell displacement between the groups. There were no significant differences between the groups in barbell velocity or lifting time for the whole movement nor differences between the groups for any of the kinematic variables in the pre-sticking, sticking, or post-sticking regions. When combining the data from the two groups, there was a significant weak negative correlation between relative strength and barbell displacement throughout the whole movement. Conclusions: These findings suggest that distinct levels of relative strength may not influence lifting kinematics in 90-degree back squats among recreationally trained participants.

Introduction: The concept of core strength refers to the ability of the core muscles to transfer, absorb and re-direct energy, and generate force/torque while providing proximal stability for distal mobility of the limbs. The aim of the present study was to examine the effects of an 8-week heavy-resistance core strength training (HR-CST) program on upper-body strength and power performance in young athletes. The secondary aim was to examine the role of sport-specific training background (kayak sprinters vs. swimmers) and sex (males vs. females).Methods: Eighteen national-level junior athletes (age: 17.1 ± 1.1 years, body height: 178 ± 7.8 cm, body mass: 70.2 ± 10.4 kg, 12 males, 6 females) competing in kayak sprint (n = 6) and swimming (n = 12) volunteered to participate. During the 8-week intervention period, half (i.e., 45 min) of the regular strength training program was replaced with HR-CST. Pre and post intervention, upper-body strength and power (i.e., maximal isokinetic stroke force [MIF] and power [MIP]) were tested by means of a maximal stroke test using a paddle ergometer. Additionally, peak (PP₂₀) and average power (AP₂₀) was determined in a 20-s all-out stroke test.Results: Paired sample t-tests indicated that PP₂₀ and AP₂₀ were significantly improved by 12.8% (p < 0.001, ES = 0.30) and 11.9% (p < 0.001, ES = 0.28), respectively, following HR-CST. No statistical changes were observed in MIF and MIP (p > 0.05, 0.19 ≤ ES ≤ 0.63).Conclusion: 8 weeks of HR-CST appears to be an effective means to improve upper-body strength and power performance in national-level junior kayak sprinters and swimmers. Our results suggest that a dynamic high-intensity core strength-training is a viable option for improving their performance in a periodized pre-season program and should be considered.

Introduction Climbing has evolved from an obscure outdoor sport to a predominantly indoor sport with the rise of mainstream climbing on artificial walls. Reported climbing-related injuries were predominantly chronic and may be avoided with proper planning of training. All climbers, regardless of age and gender, are training on the same routes and perform similar movements; however, few studies have investigated gender-specific injuries in climbing. Objectives Assess the distribution of chronic climbing injuries in an international population with gender-specific analyses and assess the impact of the person’s training focus or aim of training on those injuries. Methods A cross-sectional survey using a web-based item-driven questionnaire was created and promoted using social media and several climbing media stakeholders. All climbers engaged in either sport climbing, bouldering or traditional climbing were included. Results The survey received 1513 responses (877 men, 427 women and 9 not reporting gender), of which 50.3% (n=665; 51.4% men and 48.0% women) had experienced an injury in the past 12 months. There were significant differences in injuries in feet/ankle (p=0.014), neck (p=0.03), head (p=0.0001), shoulder (p=0.001), elbow (p=0.021) and fingers (p=0.003). Conclusion Over 50% of the climbers experienced an injury in the past 12 months. The most common injuries were to the shoulders (women) and fingers (men). There were significant differences between the genders regarding injury site and prevalence. The gender differences may be affected by the aim for training and the style of climbing.

Editorial: Injuries, injury prevention and training in climbing

Background: Climbing is an intricate sport composed of various disciplines, holds, styles, distances between holds, and levels of difficulty. In highly skilled climbers the potential for further strength-specific adaptations to increase performance may be marginal in elite climbers. With an eye on the upcoming 2024 Paris Olympics, more climbers are trying to maximize performance and improve training strategies. The relationships between muscular strength and climbing performance, as well as the role of strength in injury prevention, remain to be fully elucidated. This narrative review seeks to discuss the current literature regarding the effect of resistance training in improving maximal strength, muscle hypertrophy, muscular power, and local muscular endurance on climbing performance, and as a strategy to prevent injuries. Main Body: Since sport climbing requires exerting forces against gravity to maintain grip and move the body along the route, it is generally accepted that a climber`s absolute and relative muscular strength are important for climbing performance. Performance characteristics of forearm flexor muscles (hang-time on ledge, force output, rate of force development, and oxidative capacity) discriminate between climbing performance level, climbing styles, and between climbers and non-climbers. Strength of the hand and wrist flexors, shoulders and upper limbs has gained much attention in the scientific literature, and it has been suggested that both general and specific strength training should be part of a climber`s training program. Furthermore, the ability to generate sub-maximal force in different work-rest ratios has proved useful, in examining finger flexor endurance capacity while trying to mimic real-world climbing demands. Importantly, fingers and shoulders are the most frequent injury locations in climbing. Due to the high mechanical stress and load on the finger flexors, fingerboard and campus board training should be limited in lower-graded climbers. Coaches should address, acknowledge, and screen for amenorrhea and disordered eating in climbers. Conclusion: Structured low-volume high-resistance training, twice per week hanging from small ledges or a fingerboard, is a feasible approach for climbers. The current injury prevention training aims to increase the level of performance through building tolerance to performance-relevant load exposure and promoting this approach in the climbing field.

Purpose: Power output is dependent on the load used during exercise such as bench-press throw (BPT). Attentional focus (external [EXT] vs internal [INT]) during exercise significantly modulates power performance. The purpose of the present study was to examine the effects of load and attentional focus on mechanical parameters during BPT. Methods: In a crossover study, 31 resistance-trained men (mean age 23.5 [3.0] y) performed BPT at 30% (light), 50% (moderate), and 70% (heavy) of 1-repetition maximum (1-RM) using an INT or EXT focus of attention in randomized order. A linear encoder was used to identify barbell vertical displacement, throw time, peak/average velocity, force, and power during the concentric lifting phase. Results: Statistical analysis revealed significant load × focus interaction effects for velocity and vertical displacement (P ≤ .045; 0.66 ≤ d ≤ 0.89). Post hoc analyses indicated significantly larger velocities and displacements at 30% and 70% of 1-RM in favor of EXT (P ≤ .038; 0.79 ≤ d ≤ 1.13) but similar values at 50% of 1-RM (P > .05). Furthermore, significant main effects of load were found for throw time, force, and power (P < .001; 4.20 ≤ d ≤ 14.0). While time and force gradually increased with higher loads (P < .001; 1.45 ≤ d ≤ 14.0), power output was larger at 50% compared with 30% and 70% 1-RM (P < .001; 3.09 ≤ d ≤ 7.07), irrespective of attentional focus. Conclusions: The present findings indicated that practitioners may use EXT over INT attentional focus to enhance velocity and vertical displacement during BPT at light and heavy loads (ie, 30% and 70% 1-RM). At moderate loads (ie, 50% 1-RM), mechanical bench-press parameters appear to be less affected by attentional focus.

The aim of the present study was to examine whether relative strength influences lifting kinematics (e.g., lifting time, barbell velocity, vertical displacement) during the bench press (BP) exercise with healthy men. Loaded BP 6-repetition maximum normalized to body mass (i.e., relative strength) was examined in 110 resistance-trained men (age: 22.9 ± 2.5 years, height: 180.9 ± 6.9 cm, body mass: 80.3 ± 7.9 kg), by analysing lifting kinematics using a linear encoder. According to relative BP strength, subjects were classified as beginners, recreationally trained, intermediate, and advanced. Results showed that in the intermediate (p = 0.004, ES = 0.85) and advanced (p = 0.016, ES = 0.81) groups barbell velocity was lower in the sticking region of the BP action, compared with beginners, however there were no significant differences between groups for vertical displacement (p = 0.122–1.000) and lifting time (p = 0.052–1.000). These findings suggest that greater relative strength improves the capacity to perform the eccentric but not the concentric phase of BP. Enhanced barbell lowering indicates that the sticking region is caused by a high demand for eccentric force production during biomechanically disadvantageous conditions.