Acute Effects of Static vs. Ballistic Stretching on Strength and Muscular Fatigue Between Ballet Dancers and Resistance-Trained Women

Acute and long-term effects of two different static stretching training protocols on range of motion and vertical jump in preadolescent athletes

This study examined the acute and long-term effects of two static stretching protocols of equal duration, performed either as a single stretch or multiple shorter duration repetitions on hip hyperextension range of motion (ROM) and single leg countermovement jump height (CMJ). Thirty female gymnasts were randomly assigned to stretching (SG) or control groups (CG). The SG performed two different protocols of static stretching, three times per week for 9 weeks. One leg performed repeated stretching (3 × 30 s with 30 s rest) while the other leg performed a single stretch (90 s). The CG continued regular training. ROM and CMJ were measured pre- and 2 min post-stretching on weeks 0, 3, 6, 9, and 3 weeks into detraining. CMJ height increased over time irrespective of group (main effect time, p = 0.001), with no statistical difference between groups (main effect group, p = 0.272). Three-way ANOVA showed that, CMJ height after stretching was not affected by either stretching protocol at any time point (p = 0.503 to 0.996). Both stretching protocols equally increased ROM on weeks 6 (10.9 ± 13.4%, p < 0.001, d = 0.42), and 9 (21.5 ± 13.4%, p < 0.001, d = 0.78), and this increase was maintained during detraining (17.0 ± 15.0%, p < 0.001, d = 0.68). No increase in ROM was observed in the CG (p > 0.874). Static stretching of long duration applied either as single or multiple bouts of equal duration, results in similar acute and long-term improvements in ROM. Furthermore, both stretching protocols do not acutely affect subsequent CMJ performance, and this effect is not influenced by the large increase in ROM and CMJ overtime.

The Effects of Whole-Body Vibration on Fatigue in Vertical Jump Performance and Isometric Mid-Thigh Pull Measures

The purpose of this study is to determine the effects of coupling WBV and acute muscular fatigue to determine its effects on countermovement vertical jump (CMVJ) performance and isometric mid-thigh pull (IMTP). Twenty-eight healthy active adults volunteered for five-day study. Testing sessions 2–5 included one of four conditions: No WBV and no fatigue (CON), WBV and fatigue (WBV + FAT), WBV and no fatigue (WBV), and no WBV and fatigue (FAT). WBV was performed using a frequency of 50 Hz and a low amplitude while performing quarter squats for a total of 4 min with a 30 s rest or work ratio. Lower-body fatigue induced using Bosco fatigue protocol. CMVJ and IMTP were performed on force plates. SPSS was used to perform a 2 × 2 Repeated Measures ANOVA. Significant main effects were found for fatigue in CMVJ-height and CMVJ-peak ground reaction force, no significant main effect for WBV, and no significant interactions. Lower-body fatigue decreases vertical jump performance, and WBV did not attenuate the detrimental effects of lower-body fatigue.

[Fatigue and quality of life among professional ballroom dancers in Brazil]

The scope of this study was to analyze the relationship between quality of life, fatigue and injuries among professional Brazilian ballroom dancers. A total of 320 professionals from the five regions of Brazil participated, and the data were collected through a self-administered online questionnaire concerning general information, WHOQOL-bref, Yoshitake Fatigue Questionnaire and Injury Identification in Dancers Questionnaire. For data analysis, descriptive statistics were used, followed by inferential analysis and the Multiple Linear Regression test. The results show that greater fatigue is associated with a negative quality of life, revealing that, for each additional increment in total fatigue, the quality of life is expected to decrease by 0.218 points in the physical domain; 0.226 points in the psychological domain; 0.420 points in the social domain; and 0.304 points in the environmental domain. In contrast, the incidence and intensity of injuries were not associated with quality of life. The conclusion drawn is that the context of professional ballroom dance can influence both the presence of fatigue and the quality of life. It is suggested that health professionals working with these dancers perform multifactorial interventions in order to reduce fatigue, attenuating its effects on quality of life.

Mechanisms underlying performance impairments following prolonged static stretching without a comprehensive warm-up

Whereas a variety of pre-exercise activities have been incorporated as part of a "warm-up" prior to work, combat, and athletic activities for millennia, the inclusion of static stretching (SS) within a warm-up has lost favor in the last 25 years. Research emphasized the possibility of SS-induced impairments in subsequent performance following prolonged stretching without proper dynamic warm-up activities. Proposed mechanisms underlying stretch-induced deficits include both neural (i.e., decreased voluntary activation, persistent inward current effects on motoneuron excitability) and morphological (i.e., changes in the force-length relationship, decreased Ca²⁺ sensitivity, alterations in parallel elastic component) factors. Psychological influences such as a mental energy deficit and nocebo effects could also adversely affect performance. However, significant practical limitations exist within published studies, e.g., long-stretching durations, stretching exercises with little task specificity, lack of warm-up before/after stretching, testing performed immediately after stretch completion, and risk of investigator and participant bias. Recent research indicates that appropriate durations of static stretching performed within a full warm-up (i.e., aerobic activities before and task-specific dynamic stretching and intense physical activities after SS) have trivial effects on subsequent performance with some evidence of improved force output at longer muscle lengths. For conditions in which muscular force production is compromised by stretching, knowledge of the underlying mechanisms would aid development of mitigation strategies. However, these mechanisms are yet to be perfectly defined. More information is needed to better understand both the warm-up components and mechanisms that contribute to performance enhancements or impairments when SS is incorporated within a pre-activity warm-up.

Postactivation potentiation effects of Back Squat and Barbell Hip Thrust exercise on vertical jump and sprinting performance

BACKGROUND

This study aimed to determine and compare the post-activation potentiation (PAP) effects of the Back Squat (SQ-PAP) and Hip Thrust (HT-PAP) exercises in terms of vertical jump height (VJ), 20-yard dash and 40-yard dash time in physically active university students. Considering the Force-vector theory, it was hypothesized that HT-PAP would induce greater potentiation for 40-yard dash than SQ-PAP whereas SQ-PAP would induce greater potentiation for 20-yard dash and VJ than HT-PAP.

METHODS

Seventeen kinesiology and exercise science students (8 male and 9 female) who resistance train at least 3 times/week (age, 21.71±1.49 years; body mass, 75.58±11.89 kg; height, 173.98±11.88 cm and training experience 5.47±2.00 years) joined this study. They performed three experimental sessions namely; baseline (BL), SQ-PAP loading session and HT-PAP loading session with 48 hours interval with a randomized open crossover study design. BL session was also accepted as control and familiarization session. SQ-PAP and HT-PAP exercises were performed roughly at 90% of 1 Repetition maximum (1 RM) of the subjects with three repetitions. Subjects were tested for vertical jump height (VJ), 20-yard dash and 40-yard dash time before and 8 minutes after each PAP loading exercise.

RESULTS

Statistical analysis revealed that the potentiation effects of SQ-PAP and HT-PAP exercises on VJ height, 20-yard and 40-yard dash were similar that none of the loading exercises with 8 min rest interval had any increasing or detrimental performance effect on VJ (P=0.923), 20-yard dash (P=0.133) as well 40-yard dash time (P=0.570).

CONCLUSIONS

These findings demonstrate that none of the loading protocols with above mentioned exercises have any detrimental or improving effects on VJ height, 20-yard dash and 40-yard dash time for physically active university students who joined this study. Although no acute potentiation effect has been found, this study also shows that SQ-PAP, HT-PAP exercises can be used interchangeably and safely to avoid training monotony during longer training periods for chronic adaptations.

Acute Effects of Intermittent and Continuous Static Stretching on Hip Flexion Angle in Athletes with Varying Flexibility Training Background

Τhis study examined changes in hip joint flexion angle after an intermittent or a continuous static stretching protocol of equal total duration. Twenty-seven female subjects aged 19.9 ± 3.0 years (14 artistic and rhythmic gymnasts and 13 team sports athletes), performed 3 min of intermittent (6 × 30 s with 30 s rest) or continuous static stretching (3 min) of the hip extensors, with an intensity of 80–90 on a 100-point visual analogue scale. The order of stretching was randomized and counterbalanced, and each subject performed both conditions. Hip flexion angle was measured with the straight leg raise test for both legs after warm-up and immediately after stretching. Both stretching types equally increased hip flexion angle by ~6% (continuous: 140.9° ± 20.4° to 148.6° ± 18.8°, p = 0.047; intermittent: 141.8° ± 20.3° to 150.0° ± 18.8°, p = 0.029) in artistic and rhythmic gymnasts. In contrast, in team sports athletes, only intermittent stretching increased hip flexion angle by 13% (from 91.0° ± 7.2° to 102.4° ± 14.5°, p = 0.001), while continuous stretching did not affect hip angle (from 92.4° ± 6.9° vs. 93.1° ± 9.2°, p = 0.99). The different effect of intermittent vs. continuous stretching on hip flexion between gymnasts and team sports athletes suggests that responses to static stretching are dependent on stretching mode and participants training experience.

Acute Effects of Proprioceptive Neuromuscular Facilitation on Peak Torque and Muscle Imbalance

BACKGROUND

The effects of proprioceptive neuromuscular facilitation (PNF) stretching on muscle imbalance are not fully understood. The aim of this study was to examine the acute effects of PNF stretching on knee extension and flexion peak torque (PT), as well as the conventional and functional hamstrings to quadriceps (H:Q) ratios.

METHODS

Fifteen men (age = 22 ± 1 years; body mass = 76 ± 12 kg; height = 176 ± 7 cm) and fifteen women (age = 22 ± 2 years; body mass = 63 ± 8 kg; height = 161 ± 5 cm) performed concentric quadriceps and hamstrings, and eccentric hamstrings muscle actions at different angular velocities (60, 180, and 300°·s^-1 concentric; 60 and 180°·s^-1 eccentric) before and after a bout of PNF stretching, and a control condition.

RESULTS

Neither PNF or control conditions affected concentric PT or H:Q ratios (p > 0.05), apart from knee extension at 60°·s^-1 in men (p = 0.001). However, there was a reduction in hamstrings eccentric PT in both control and PNF conditions for men and women (p = 0.003).

CONCLUSIONS

PNF stretching of the hamstrings may not adversely affect the H:Q ratios, and consequently not negatively affect injury risk associated with muscular strength imbalances.

Acute Effects of Dynamic Stretching on Muscle Flexibility and Performance: An Analysis of the Current Literature

Stretching has long been used in many physical activities to increase range of motion (ROM) around a joint. Stretching also has other acute effects on the neuromuscular system. For instance, significant reductions in maximal voluntary strength, muscle power or evoked contractile properties have been recorded immediately after a single bout of static stretching, raising interest in other stretching modalities. Thus, the effects of dynamic stretching on subsequent muscular performance have been questioned. This review aimed to investigate performance and physiological alterations following dynamic stretching. There is a substantial amount of evidence pointing out the positive effects on ROM and subsequent performance (force, power, sprint and jump). The larger ROM would be mainly attributable to reduced stiffness of the muscle-tendon unit, while the improved muscular performance to temperature and potentiation-related mechanisms caused by the voluntary contraction associated with dynamic stretching. Therefore, if the goal of a warm-up is to increase joint ROM and to enhance muscle force and/or power, dynamic stretching seems to be a suitable alternative to static stretching. Nevertheless, numerous studies reporting no alteration or even performance impairment have highlighted possible mitigating factors (such as stretch duration, amplitude or velocity). Accordingly, ballistic stretching, a form of dynamic stretching with greater velocities, would be less beneficial than controlled dynamic stretching. Notwithstanding, the literature shows that inconsistent description of stretch procedures has been an important deterrent to reaching a clear consensus. In this review, we highlight the need for future studies reporting homogeneous, clearly described stretching protocols, and propose a clarified stretching terminology and methodology.

Flexibility training in preadolescent female athletes: Acute and long-term effects of intermittent and continuous static stretching

This study compared the acute and long-term effects of intermittent and continuous static stretching training on straight leg raise range of motion (ROM). Seventy-seven preadolescent female gymnasts were divided into a stretching (n = 57), and a control group (n = 20). The stretching group performed static stretching of the hip extensors of both legs, three times per week for 15 weeks. One leg performed intermittent (3 × 30 s with 30 s rest) while the other leg performed continuous stretching (90 s). ROM pre- and post-stretching was measured at baseline, on weeks 3, 6, 9, 12, 15 and after 2 weeks of detraining. ROM was increased during both intermittent and continuous stretching training, but remained unchanged in the control group. Intermittent stretching conferred a larger improvement in ROM compared to both continuous stretching and control from week 3, until the end of training, and following detraining (p = 0.045 to 0.001 and d = 0.80 to 1.41). During detraining, ROM after the intermittent protocol decreased (p = 0.001), while it was maintained after the continuous protocol (p = 0.36). Acute increases in ROM following the intermittent stretching were also larger than in the continuous (p = 0.038). Intermittent stretching was more effective than continuous, for both long-term and acute ROM enhancement in preadolescent female athletes.