BACKGROUND: The back squat is an integral aspect of any resistance training program to improve athletic performance. It is also used for injury prevention of the lower limbs.
OBJECTIVE: The purpose of this study was to examine the effect of back squat training at different intensities on strength and flexibility of the hamstring muscle group (HMG).
METHODS: Twenty-two male recreational bodybuilders with at least two years of experience in resistance training were recruited to participate in a nine-week training program. They were randomly assigned to a heavy back squat group (90-95% of one repetition maximum) or a moderate-intensity back squat group (60-65% of one repetition maximum).
RESULTS: The heavy back squat group resulted in a significantly (p < 0.001) increased in one repetition maximum strength but a significant (p < 0.001) reduction in HMG flexibility when compared to their counterparts. The results of the study indicate that while a heavy back squat training program is effective in improving strength, it has an adverse effect on the flexibility of the HMG.
CONCLUSION: The implication of this study is that there is a tradeoff between strength and flexibility and trainers should select the appropriate training protocols for their athletes to maximize athletic performance.
METHODS: In experiment 1 (n = 10), we tested the direction of force exerted in an isometric aiming task before and after 40 repetitions of 2-s maximal-force ballistic contractions toward a single directional target. In experiment 2 (n = 12), each participant completed three training conditions in a counterbalanced crossover design. In two conditions, both the aiming task and the training were conducted in the same (neutral) forearm posture. In one of these conditions, the training involved weak forces to determine whether the level of neural drive during training influences the degree of bias. In the third condition, high-force training contractions were performed in a 90° pronated forearm posture, whereas the low-force aiming task was performed in a neutral forearm posture. This dissociated the extrinsic training direction from the pulling direction of the trained muscles during the aiming task.
RESULTS: In experiment 1, we found that aiming direction was biased toward the training direction across a large area of the work space (approximately ±135°; tested for 16 targets spaced 22.5° apart), whereas in experiment 2, we found systematic bias in aiming toward the training direction defined in extrinsic space, but only immediately after high-force contractions.
CONCLUSION: Our findings suggest that bias effects of training involving strong neural drive generalize broadly to untrained movement directions and are expressed according to extrinsic rather than muscle-based coordinates.
MATERIALS AND METHODS: This was a pilot prospective, randomized trial of women aged ≥18 years with SUI symptoms who underwent PFMEs at University Malaya Medical Centre from October 2011 to October 2013. The patients were randomly divided into two groups: control (PFMEs alone) and VKD (PFMEs with VKD biofeedback). The patients underwent 16 weeks of pelvic floor training, during which they were assessed using Australian pelvic floor questionnaires and modified Oxford scales for pelvic floor muscle strength at week 0, 4, and 16.
RESULTS: Forty patients were recruited (control 19, VKD 21). Three patients in the control group dropped out during week 16 training, whereas the VKD group had no dropouts. The VKD group reported significantly earlier improvement in SUI scores, as assessed by the Australian pelvic floor questionnaires (P = .035) at week 4. However, there was no significant difference between the groups' SUI scores at week 16. Pelvic floor muscle strength was significantly better in the VKD group at week 4 (P = .025) and week 16 (P = 0.001). The subjective cure rate was similar in both groups at week 16 (62.5% for control and 61.9% for VKD) (P = 0.742).
CONCLUSION: Using the VKD resulted in significant early improvement in SUI scores, and pelvic muscle strength had improved significantly by the end of the study. The VKD proved useful as an adjunct for pelvic floor training.
METHOD: A quasi-randomized controlled trial was conducted recruiting students from two different higher learning institutions in Kuantan, Pahang, Malaysia. Students are selected after fulfilling the criteria such as body mass index (BMI) of ≥23kg/m2, no chronic diseases that may influence by exercise, no significant changes in body weight within two months and not taking any medications or supplements. One institution was purposely chosen as a simulation-based group and another one control group. In the simulation-based group, participants were given a booklet and CD to do aerobic and resistance exercise for a minimum of 25min per day, three times a week for 10 weeks. No exercise was given to the control group. Participants were measured with the International Physical Activity Questionnaire (IPAQ), BMI, waist circumference (WC), body fat percentage before and after 10 weeks of simulation-based exercise.
RESULTS: A total of 52 (control: 25, simulation-based: 27) participants involved in the study. There was no baseline characteristics difference between the two groups (p>0.005). All 27 participants in the simulation-based group reported performing the exercise based on the recommendation. The retention rate at three months was 100%. No adverse events were reported throughout the study. Better outcomes (p<0.001) were reported among participants in the simulation-based group for BMI, WC and body fat percentage.
CONCLUSIONS: The findings of this study indicate that the simulation-based exercise programme may be feasible for an overweight adult in higher learning institutes. As a feasibility study this is not powered to detect significant differences on the outcomes. However, participants reported positive views towards the recommended exercise with significant improvements in body mass index, body fat percentage and reduced the waist circumference.
METHODS: A total of 51 subjects qualified to take part in this quasi-experimental study. They were assigned to either the resistance exercise group (n = 26) or control group (n = 25). The mean age of the 45 participants who completed the program was 70.7 (SD = 6.6). The exercise group met twice per week and performing one to three sets of 8 to 10 repetitions for each of nine lower-limb elastic resistance exercises. All exercises were conducted at low to moderate intensities in sitting or standing positions. The subjects were tested at baseline and 6 and 12 weeks into the program.
RESULTS: The results showed statistically significant improvements in lower-limb muscle strength as measured by five times sit-to-stand test (%Δ = 22.6) and dynamic balance quantified by the timed up-and-go test (%Δ = 18.7), four-square step test (%Δ = 14.67), and step test for the right (%Δ = 18.36) and left (%Δ = 18.80) legs. No significant changes were observed in static balance as measured using the tandem stand test (%Δ = 3.25), and one-leg stand test with eyes opened (%Δ = 9.58) and eyes closed (%Δ = -0.61) after completion of the program.
CONCLUSION: The findings support the feasibility and efficacy of a simple and inexpensive resistance training program to improve lower-limb muscle strength and dynamic balance among the institutionalized older adults.
METHOD: A meta-analysis was conducted to determine the potential impact of isometric exercise on IOP and OPP. The literature on the relationship between isometric resistance exercise and IOP was systematically searched according to the "Cochrane Handbook" in the databases of Pubmed, Web of Science, EBSCO, and Scopus through December 31, 2020. The search terms used were "exercise," "train," "isometric," "intraocular pressure," and "ocular perfusion pressure," and the mean differences of the data were analyzed using the Stata 16.0 software, with a 95% confidence interval.
RESULTS: A total of 13 studies, which included 268 adult participants consisting of 162 men and 106 women, were selected. All the exercise programs that were included were isometric resistance exercises of the lower limbs with intervention times of 1min, 2min, or 6min. The increase in IOP after intervention was as follows: I2=87.1%, P=0.001 using random-effects model combined statistics, SMD=1.03 (0.48, 1.59), and the increase in OPP was as follows: I2=94.5%, P=0.001 using random-effects model combined statistics, SMD=2.94 (1.65, 4.22), with both results showing high heterogeneity.
CONCLUSION: As isometric exercise may cause an increase in IOP and OPP, therefore, people with glaucoma and related high risk should perform isometric exercise with caution.
DESIGN: A meta-analysis was conducted to determine the potential impact of blood flow restriction on patients with knee injuries. PubMed, EBSCO, and Web of Science databases were searched for eligible studies from January 2000 until January 2020. The mean differences of the data were analyzed using Revman 5.3 software with a 95% confidence interval.
RESULTS: Nine studies fulfilled the inclusion criteria. These studies involved 179 patients who received L-BFR, 96 patients who underwent high-load resistance training, and another 94 patients who underwent low-load resistance training. The analysis of pooled data showed that patients in both the L-BFR (standardized mean difference, 0.83 [0.53, 1.14], P < 0.01) and high-load resistance training (standardized mean difference, -0.09 [-0.43, 0.24], P = 0.58) groups experienced an increase in muscle strength after the training. In addition, pain score was significantly reduced in the L-BFR group compared with the other two groups (standardized mean difference, -0.61 [-1.19, -0.03], P = 0.04).
CONCLUSIONS: Muscle strength increased after L-BFR and high-load resistance training compared with low-load resistance training. Furthermore, pain score was significantly reduced after L-BFR. Hence, L-BFR is a potential intervention to be applied in rehabilitation of knee injuries.
OBJECTIVES: This study adopts a systematic literature review to (1) examine the effects of resistance training on the performance of adolescent swimmers, and (2) summarize their training methods and intensity.
METHODS: The literature search was undertaken in five international databases: the SCOUPS, PubMed, EBSCOhost (SPORTDiscus), CNKL, Web of Science. The searches covered documents in English and Chinese published until 30th December 2020. Electronic databases using various keywords related to "strength training" and "adolescent swimmers" were searched. Sixteen studies met the inclusion and exclusion criteria where the data was then systematically reviewed using the PRISMA guideline. Furthermore, the physical therapy evidence database (PEDro) scale was used to measure each study's scientific rigor.
RESULTS: This review found that to improve the swimming performance of adolescents, two types of resistance training were used, specifically in water and on land, where both types of training can improve swimming performance. In addition, training with two types of resistance machines were better in the water than with one equipment. Resistance training can improve the swimming performance of adolescent swimmers at 50 m, 100 m, 200 m and 400 m distances. However, most studies only focused on the swimming performance at 50 m and 100 m lengths. A low-intensity, high-speed resistance training programme is recommended for adolescent swimmers to obtain the best training results.
CONCLUSION: Water or land resistance training can improve the swimming performance. Given that both types of exercises have their strengths and weaknesses, combining these methods may enhance the swimmers' performance. In addition, despite the starting and turning phases consuming up to one-third of the total swimming time for short distances, literature in this area is limited.
SYSTEMATIC REVIEW REGISTRATION: https://www.crd.york.ac.uk/prospero, identifier: CRD42021231510.