Lower extremity isokinetic strength characteristics of amateur boxers

Proprioceptive neuromuscular facilitation warm-ups: a key to improved isokinetic performance

This study examined the immediate effects of proprioceptive neuromuscular facilitation warm-ups on isokinetic strength, endurance, and body balance in 50 football players. Data collection spanned four sessions, each separated by full rest. The isokinetic strength of the hip, knee, and ankle flexion and extension was measured using a dynamometer at 60°/s, 180°/s, and 240°/s. Endurance was assessed at 240°/s through 25 repetitions, analyzing peak torque changes. On the first day, participants performed general warm-ups followed by balance and strength tests. Subsequent sessions repeated these tests with additional measurements. Results showed that proprioceptive neuromuscular facilitation warm-ups significantly improved the static and dynamic balance compared to other methods. Peak torque measurements at all speeds also highlighted the superior effectiveness of proprioceptive neuromuscular facilitation warm-ups. Additionally, this warm-up approach provided greater acute enhancement in knee joint isokinetic endurance. In conclusion, proprioceptive neuromuscular facilitation warm-ups increased the isokinetic strength, endurance, and balance in football players. Incorporating proprioceptive neuromuscular facilitation warm-ups into football training especially for lower body preparation is recommended. Combining them with active warm-ups may further boost acute performance.

Acute effects of tissue flossing on boxers with chronic knee pain

Objectives

To explore the acute intervention effects of tissue flossing on chronic knee pain (CKP) in boxers.

Methods

Eighteen boxers with CKP (12 male/6 female) were randomly divided into an experimental group (EG) with tissue flossing (n = 9) and a control group (CG) (n = 9). The visual analog scale (VAS), Lysholm knee function score, flexion range of motion (ROM), maximal isometric extensor muscle strength, and stability of the knee were measured pre- and post-intervention (EG: 3-minute tissue flossing, CG: rest).

Results

VAS (F = 15.849, p = 0.001, η 2 p = 0.498) and Lysholm knee function (F = 9.327, p = 0.008, η 2 p = 0.357) significantly improved more in the EG than in the CG. There was a significant difference for maximal isometric extensor muscle strength (F = 17.769, p = 0.001, η 2 p = 0.542) and knee stability (F = 13.844, p = 0.002, η 2 p = 0.464) but no significant difference for ROM (F = 1.218, p = 0.287, η 2 p = 0.075) between the EG and CG.

Conclusion

Tissue flossing can reduce knee pain, improve knee function, increase knee extensor strength, and improve knee stability in boxers with CKP.

Neuromuscular factors predicting lower limb explosive strength in male college sprinters

Purpose

This study aimed to explore the effects of neural and muscular factors on lower limb explosive strength in male college sprinters, and build models based on those factors to identify the key neuromuscular factors that predict the rate of force development (RFD) and 30 m sprint time.

Method

15 male college sprinters were recruited in this study, with 100 m personal best times under 10.93 s. The neuromuscular data were collected by H-reflex and V-wave, isokinetic muscle strength, vertical jumps, and 30 m sprint tests. Pearson correlation and multiple stepwise regression were used for data analysis. The level of statistical significance was set at p ≤ 0.05 for all analyses.

Results

30 m sprint time had a significant moderate positive correlation with Achilles tendon stiffness (r = 0.50, p = 0.05, 95%CI: 0.01-0.81) and a significant moderate negative correlation with the H-index (r = -0.54, p = 0.04, 95%CI: 0.82 to -0.03), V wave (V/MmaxA, r = -0.59, p = 0.02, 95%CI: 0.85 to -0.11) and the eccentric strength of Hamstring (HECC, r = -0.53, p = 0.04, 95%CI: 0.82 to -0.03). The rate of force development (RFD) had a significant positive correlation with H reflex (Hmax/Mmax, r = 0.57, p = 0.03.95%CI:0.08-0.84), and the eccentric strength of Quadriceps (QECC, r = 0.53, p = 0.04, 95%CI: 0.02-0.82). V/MmaxA and HECC were identified as predictors of 30 m sprint time, and the R 2 explained 57.5% of the variance. Vertical stiffness and QECC explained 82.7% of the variation in the RFD.

Conclusion

This study found that V/MmaxA and HECC were predictive factors of 30 m sprint time, vertical stiffness and QECC were the predictive factors of RFD. Neural factors such as the α-motoneurons excitability of the spinal and supraspinal centers, have a greater influence on lower limb explosive strength in male college sprinters. Therefore, training related to the neural function of sprinters should be emphasized. In addition, H reflex and V wave can be used widely to assess and monitor the neural function of sprinters in future research. The impact of neural drive on muscles in different levels and sexes of sprinters, and the neuromuscular modulation during muscle contractions can be further explored.

Effects of two warm-up protocols on isokinetic knee strength, jumping ability and sprint swimming performance in competitive swimmers

The purpose of this study was to examine the effects of different dryland warm-up protocols on knee isokinetic strength, vertical jumping, and sprint performance in competitive swimmers. Twenty-four male swimmers were randomly assigned to the FIFA 11 + group (n = 12) or the post-activation performance enhancement (PAPE) group (n = 12). The FIFA 11 + group performed the FIFA 11 + warm-up program three times per week for 6 weeks, whereas the PAPE group consisted of performing general activities and three sets of five drop jumps. Performance test included concentric (con) and eccentric (ecc) isokinetic strength of the quadriceps (Q) and hamstrings (H) of the dominant (DL) and non-dominant (NDL) limbs at three angular velocities, countermovement jump (CMJ), squat jump (SJ) and a 50-m time trial. The conventional (Hcon: Qcon) and functional (Hecc: Qcon) ratios were calculated pre- and post- intervention. The FIFA 11 + group showed a significant increase in DL-Hcon (p < 0.05, ES = 1.0-1.8), and NDL-Hcon (p < 0.05, ES = 1.0-1.6) in all angular velocities, and DL-Qcon (p < 0.05, ES = 0.9) at 60°·s- 1. The PAPE group significantly improved DL-Qcon at 180°·s- 1, 240°·s- 1 (both p < 0.05, ES = 1.0), and NDL-Qcon at 240°·s- 1 (p < 0.05, ES = 0.9). Additionally, FIFA 11 + showed significant improvement in DL-Hcon and NDL-Hcon (both p < 0.05, ES = 0.9-1.8) compared with PAPE. FIFA 11 + increased DL-Hcon: Qcon60 (p < 0.05, ES = 1.1) and NDL- Hcom: Qcon60,240 (both p < 0.05, ES = 1.2) compared with PAPE. Both groups significantly improved CMJ (FIFA 11 + p < 0.01, ES = 0.4 and PAPE p < 0.01, ES = 0.3), SJ (both p < 0.01, ES = 0.6) and 50-m swimming performance (FIFA 11 + p < 0.05, ES = -0.8 and PAPE p < 0.05, ES = -0.6).Both warm-up protocols showed similar improvements in jumping ability and sprint swimming performance. The FIFA 11 + seemed more efficient in improving lower limb isokinetic strength and conventional strength ratios in male competitive swimmers.

A physical fitness-evaluation system for outstanding Chinese male boxers

Background

We sought to create a system to evaluate the physical fitness of outstanding Chinese male boxers that included an evaluation index, fitness level criteria, and modeling. This system was then used to assess athletes' physical fitness and development.

Methods

Documentation, expert interviews, questionnaires, measurements, and statistical analyses were used in this study.

Results

The physical fitness evaluation system included the following three components: (1) body shape indexes (n = 4) including the backhand upper arm circumference differential, finger span height, Cottrell index, and pelvic width/shoulder width × 100; (2) body function indexes (n = 4) including relative maximum anaerobic power, relative maximal oxygen uptake, and creatine kinase and testosterone concentrations; and (3) athletic quality indexes (n = 9) including the speed strength index, the backhand straight punch strength, 3-min cumulative punching force, backhand straight punch reaction time, backhand straight punch speed, 30-m sprint, 9-min double shake jump rope, 1-min double shake jump rope, and sitting forward bend tests. A five-point grading system to evaluate physical fitness was established and an evaluation model was proposed.

Conclusions

The reference values were determined to be objective and effective using a back substitution process. Individual and differential assessments reflected the athletes' level of physical fitness. The critical values were established under the best and worst conditions and the optimal values were found to be valid and effective.

New prediction equations for knee isokinetic strength in young and middle-aged non-athletes

BACKGROUND

This study aimed to develop alternative prediction equations to predict isokinetic muscle strength at 60°/s based on anthropometric characteristics, including body mass, height, age, and sex for young and middle-aged non-athlete populations.

METHODS

Three hundred and thirty-two healthy non-athletic participants (174 females, 158 males) between 20 and 59 years underwent a 60°/s isokinetic knee joint concentric contraction test. Forty people were randomly selected for retesting to assess the reliability of the isokinetic instrument. Multivariate linear regression was used to establish extension peak torque (EPT) and flexion peak torque (FPT) prediction equations. Sixty extra participants were used individually to validate the prediction equations, and Bland Altman plots were constructed to assess the agreement of predicted values with actual measurements.

RESULTS

The result demonstrated that the instrument we used has excellent reliability. The multivariable linear regression model showed that body mass, age, and sex were significant predictors of PT (EPT: Adjusted R2 = 0.804, p < 0.001; FPT: Adjusted R2 = 0.705, p < 0.001). Furthermore, the equations we established had higher prediction accuracy than those of Gross et al. and Harbo et al. CONCLUSION: The equations developed in this study provided relatively low bias, thus providing a more suitable reference value for the knee isokinetic strength of young and middle-aged non-athletes.

Relationship between isokinetic strength of the knee joint and countermovement jump performance in elite boxers

Background

The lower limbs play a key role to develop the linear momentum for hitting power in effective boxing. The knee extensor and flexor strength guarantees the dynamic stability of boxers. The insufficient extensor strength of the lower extremities causes compensation during flexion resulting in movement errors or damage to knee joint muscles. This study was conducted to explore the isokinetic concentric strength of the knee flexor and extensor and the relationship between isokinetic knee extensors strength and countermovement jump (CMJ) performance in elite boxers.

Methods

Thirteen elite male boxers (Age: 25.15 ± 3.98 years, height 1.72 ± 0.04 m, weight 61.82 ± 10.46 kg, training years = 11.56 ± 2.67 years) performed the CMJ, and the isokinetic knee test was performed using the Biodex dynamometer.

Results

The maximal isokinetic peak torque of the knee extensor and flexor muscles was recorded at three angular velocities (60°/s, 180°/s, and 240°/s) on both sides of the legs. The relative peak value of torque in the knee extensors decreased significantly with increasing angular velocity. A difference in relative peak torque (RPT) was only seen at 60°/s in knee flexors. However, the H/Q ratio increased as the velocity increased from 60°/s to 240°/s (P < 0.05). The highest peak torque was found in the knee extensors at a velocity of 240°/s (r = 0.73, P < 0.001). The correlation between RPT and vertical jump height was the strongest at 240°/s. The strongest relationship was found between the height of the CMJ and the RPT of the deficit of knee extensors.

Conclusions

We suggest that explosive force training of the isokinetic muscles should be optimally carried out at a speed of 240°/s. The results of this study provide a reference for boxers to improve their jump height and lower-limb explosive strength through isokinetic strength training of the knee flexor and extensor.