The effects of caffeine ingestion on isokinetic muscular strength: A meta-analysis

Objectives

The aims of this paper are threefold: (1) to summarize the research examining the effects of caffeine on isokinetic strength, (2) pool the effects using a meta-analysis, and (3) to explore if there is a muscle group or a velocity specific response to caffeine ingestion.

Kinesiology tape mediates soccer-simulated and local peroneal fatigue in soccer players

To investigate the efficacy of kinesiology taping in mediating the influence of fatigue on ankle sprain risk, 12 male soccer players completed single-leg dynamic balance trials pre- and post-exercise (soccer-specific protocol, isokinetic ankle inversion/eversion protocol) in each of three counter-balanced taping conditions (no tape, zinc oxide tape ZO, kinesiology tape KT). Balance was quantified as the overall stability index (OSI) and directional stability indices of platform deflection. Soccer-specific fatigue only increased OSI in the no tape condition (p = 0.03), with ZO and KT trials negating a fatigue affect. Localized fatigue increased OSI in the no tape (p = 0.01) and ZO (p = 0.05) trials, with no increase in the KT trial. A similar pattern was observed in medio-lateral and anterio-posterior balance indices. KT mediates soccer-simulated and local peroneal fatigue, with practical implications for epidemiological observations of increased injury risk during the latter stages of match play.     

肌内效贴对高强度训练后下肢训练伤的防护效果

目的 探讨肌内效贴对高强度训练后下肢训练伤的防护效果。方法 2019-06至2019-07从某部集训战士中选取51名受试者,随机分为三组：肌内效贴组(KT组)、安慰剂贴组(PT组)和静态拉伸组(SC组),每组17名。10 km武装奔袭后即刻、24 h、48 h、72 h,比较三组视觉模拟评分(VAS)、膝关节功能(ROM)、Lysholm评分、大腿周径等。结果 在训练后即刻、24 h、48 h、72 h, KT组的VAS值均低于SC组和PT组(P<0.05);KT组在训练后48 h、72 h对ROM的改善明显优于PT组和SC组(P<0.05),训练后48 h的Lysholm评分高于PT组及SC组(P<0.01);SC组在训练后72 h的VAS值低于PT组,对ROM的改善优于PT组(P<0.05)。三组不同时间的大腿周径无统计学差异。结论 肌内效贴有利于高强度训练后缓解下肢肌肉疼痛,增强膝关节稳定性,且能改善关节活动度,可用于下肢军事训练伤的防治。     

The efficacy of ice massage in the treatment of exercise-induced muscle damage

The purpose of this investigation was to, firstly, examine the effects of repeated applications of ice massage on the indirect markers associated with muscle damage using a within-subjects cross-over design and secondly, to examine how ice massage affects muscle function in both static and dynamic contractions following unaccustomed eccentric exercise. Twelve males performed damaging exercise on two separate occasions. The protocol consisted of three sets of 10 maximal eccentric repetitions of the elbow flexors using isokinetic dynamometry. Subjects were randomly assigned to an ice massage group or placebo group and received treatments immediately post-exercise, 24 and 48 h post-exercise. Muscle function (maximal isometric, slow and fast isokinetic contractions), creatine kinase, myoglobin, muscle soreness, limb girth and range of motion were measured pre, immediately post, 24, 48, 72 and 96 h post-exercise. Significant time effects were observed for all dependent variables (P<0.05). There were no significant differences between treatments. Ice massage is ineffective in reducing the indirect markers associated with exercise-induced muscle damage and enhancing recovery of muscle function in male exercisers unaccustomed to eccentric biased exercise.     

Effect of single bout versus repeated bouts of stretching on muscle recovery following eccentric exercise

ObjectivesTo analyze the effects of a single bout and repeated bouts of stretching on indirect markers of exercise-induced muscle damage.DesignA randomized controlled clinical trial at a university human research laboratory was conducted.MethodsFifty-six untrained males were randomly divided into four groups. (I) a single stretching group underwent a single bout of stretching on the quadriceps muscle; (II) an eccentric exercised group underwent eccentric quadriceps muscle contractions until exhaustion; (III) an eccentric exercise group followed by a single bout of stretching; (IV) an eccentric exercised group submitted to repeated bouts of stretching performed immediately and 24, 48, and 72 h post-exercise. Muscle stiffness, muscle soreness, maximal concentric peak torque, and plasma creatine kinase activity were assessed before exercise and 1, 24, 48, 72, and 96 h post-exercise.ResultsAll exercised groups showed significant reduction in maximal concentric peak torque and significant increases in muscle soreness, muscle stiffness, and plasma creatine kinase. There were no differences between these groups in all assessed variables, with the exception of markers of muscle stiffness, which were significantly lower in the eccentric exercise group followed by single or repeated bouts. The single stretching group showed no change in any assessed variables during the measurement period.ConclusionsMuscle stretching performed after exercise, either as single bout or as repeated bouts, does not influence the levels of the main markers of exercise-induced muscle damage; however, repeated bouts of stretching performed during the days following exercise may have favorable effects on muscle stiffness.     

Regeneration of hamstring tendons after anterior cruciate ligament reconstruction

Purpose

Primary aim of the study was analysis of hamstring tendon regeneration after anterior cruciate ligament reconstruction (ACLR). Secondary aim was analysis of isokinetic muscle strength in relation to hamstring regeneration. The hypothesis was that regeneration of hamstring tendons after ACLR occurs and that regenerated hamstring tendons contribute to isokinetic hamstring strength with regeneration distal to the knee joint line.

Methods

Twenty-two patients scheduled for ACLR underwent prospective MRI analysis of both legs. MRI parameters were tendon regeneration and morphology, muscle retraction and muscle cross-sectional area. A double-blind, prospective analysis of isokinetic quadriceps and hamstrings strength was performed.

Results

Regeneration of the gracilis tendon after ACLR occurred in all patients. Regeneration of the semitendinosus tendon occurred in 14 patients. At 1 year, the surface area of the semitendinosus and gracilis muscle decreased compared to both preoperatively (P < 0.01) and the contralateral leg (P < 0.01). The cross-sectional area of the semitendinosus muscle decreased in the absence of tendon regeneration (P = 0.05). The cross-sectional area of the gracilis muscle was greater in case of regeneration distal to the joint line (P = 0.01). Muscle retraction of the semitendinosus muscle was increased in case of nonregeneration (P = 0.02). There was no significant relationship between isokinetic flexion strength and tendon regeneration.

Conclusion

Hamstring tendons regenerated after harvest of both semitendinosus and gracilis tendons for ACLR. There was no relation between isokinetic flexion strength and tendon regeneration.

Level of evidence

Prognostic study, Level II.     

Effects of selective strengthening of tibialis posterior and stretching of iliopsoas on navicular drop,dynamic balance,and lower limb muscle activity in pronated feet: A randomized clinical trial

Objectives: Flexibility and strength are compromised in pronated feet, which could in turn lead to alteration of the dynamic balance and muscle activity in the lower extremities. This study aimed to analyze the effects of selective tibialis posterior strengthening and iliopsoas stretching on navicular drop, dynamic balance, and lower limb muscle activity in young adults with pronated feet.

Methods: Twenty-eight participants with pronated feet were randomly assigned to either the stretching and strengthening group (n = 14) or the conventional exercise group (n = 14). The stretching and strengthening group performed tibialis posterior strengthening exercises and iliopsoas stretching three times a week for 6 weeks in addition to the conventional towel curl exercises. The conventional exercise group performed towel curl exercises only. Navicular drop, dynamic balance, and lower limb muscle activity were assessed at baseline and post-intervention. A mixed model analysis of variance was performed to test the study hypothesis.

Results: Significant group effects for the activity of tibialis anterior (p = 0.003) and abductor hallucis muscle (p = 0.010), as well as for the posterolateral (p = 0.036) and composite reach scores (p = 0.018), were detected. Significant group × time interactions were observed for naviculardrop (p < 0.001), all dynamic balance components (p < 0.001), and the activity of tibialis anterior (p < 0.001) and abductor hallucis (p < 0.001).

Conclusions: This study demonstrated that inclusion of selective tibialis posterior strengthening and iliopsoas stretching in addition to the conventional towel curl exercise program could improve important clinical outcomes, such as navicular drop, muscle activity, and dynamic balance in flatfeet.     

3D 23Na MRI of human skeletal muscle at 7 Tesla: initial experience

Objective

To evaluate healthy skeletal muscle pre- and post-exercise via 7 T ²³Na MRI and muscle proton T₂ mapping, and to evaluate diabetic muscle pre- and post-exercise via 7 T ²³Na MRI.

Methods

The calves of seven healthy subjects underwent imaging pre- and post-exercise via 7 T ²³Na MRI (3D fast low angle shot, TR/TE?=?80 ms/0.160 ms, 4 mm?×?4 mm?×?4 mm) and 1 week later by ¹H MRI (multiple spin-echo sequence, TR/TE?=?3,000 ms/15–90 ms). Four type 2 diabetics also participated in the ²³Na MRI protocol. Pre- and post-exercise sodium signal intensity (SI) and proton T₂ relaxation values were measured/calculated for soleus (S), gastrocnemius (G), and a control, tibialis anterior (TA). Two-tailed t tests were performed.

Results

In S/G in healthy subjects post-exercise, sodium SI increased 8–13% (p?<?0.03), then decreased (t _1/2?=?22 min), and ¹H T₂ values increased 12–17% (p?<?0.03), then decreased (t _1/2?=?12–15 min). In TA, no significant changes in sodium SI or ¹H T₂ values were seen (?2.4 to 1%, p?>?0.17). In S/G in diabetics, sodium SI increased 10–11% (p?<?0.04), then decreased (t _1/2?=?27–37 min) without significant change in the TA SI (?3.6%, p?=?0.066).

Conclusion

It is feasible to evaluate skeletal muscle via 3D ²³Na MRI at 7 T. Post-exercise muscle ¹H T₂ values return to baseline more rapidly than sodium SI. Diabetics may demonstrate delayed muscle sodium SI recovery compared with healthy subjects.     

The effects of flexibility training on exercise‐induced muscle damage in young men with limited hamstrings flexibility

Adaptations to 6 weeks of supervised hamstring stretching training and its potential impact on symptoms of eccentric exercise‐induced muscle damage (EIMD) were studied in 10 young, untrained men with limited hamstrings flexibility. Participants performed unilateral flexibility training (experimental leg; EL) on an isokinetic dynamometer, while the contralateral limb acted as control (CL). Hip range of motion (ROM), passive, isometric, and concentric torques, active optimum angle, and biceps femoris and semitendinosus muscle thickness and ultrasound echo intensity were assessed both before and after the training. Additionally, muscle soreness was assessed before and after an acute eccentric exercise bout in both legs (EL and CL) at post‐training only. Hip ROM increased (P  < .001) only in EL after the training (EL = 10.6° vs CL = 1.6°), but no changes (P  > .05) in other criterion measurements were observed. After a bout of eccentric exercise at the end of the program, isometric and dynamic peak torques and muscle soreness ratings were significantly altered at all time points equally in EL and CL. Also, active optimum angle was reduced immediately, 48 and 72 hours post‐exercise, and hip ROM was reduced at 48 and 72 hours equally in EL and CL. Finally, biceps femoris muscle thickness was significantly increased at all time points, and semitendinosus thickness and echo intensity significantly increased at 72 hours, with no significant differences between legs. The stretching training protocol significantly increased hip ROM; however, it did not induce a protective effect on EIMD in men with tight hamstrings.     

Isokinetic knee function in healthy subjects with and without Kinesio taping

ObjectiveThis study examined the difference in the isokinetic knee performance in healthy subjects with and without the Kinesio tape application onto the skin surface overlying the vastus medialis.DesignA cross-sectional experimental study.SettingClinical setting.Participants30 healthy participants.Main outcome measuresMaximal concentric knee extension and flexion at three angular velocities (60, 120 and 180°/s) were measured with an isokinetic dynamometer. Normalized peak torque, normalized total work done and time to peak torque of knee extension and flexion were compared by repeated measures ANOVA.ResultsThere was no significant main effect in ANOVA in normalized peak torque and normalized total work done between taping conditions and angular velocities. Conversely, participants demonstrated significant shorter time to peak extension torque with the tape condition (p = 0.03). Pair-wise comparisons indicated that such time reduction (36–101 ms) occurred at all three angular velocities (p < 0.01).ConclusionThis investigation demonstrated the application of Kinesio tape did not alter the muscle peak torque generation and total work done but shortened the time to generate peak torque. This finding may contribute to the rationale in injury prevention and rehabilitation in athletes with Kinesio taping.     

Is gender influencing the biomechanical results after autologous chondrocyte implantation?

Purpose

The influence of gender on the biomechanical outcome after autologous chondrocyte implantation (ACI) including isokinetic muscle strength measurements has not been investigated. The present prospective study was performed to evaluate gender-specific differences in the biomechanical function 48 months after ACI.

Methods

Fifty-two patients (mean age 35.6 ± 8.5 years) that met our inclusion criteria, underwent ACI with Bioseed C^® and were evaluated with the KOOS score preoperatively, 6, 12 and 48 months after surgery. At final follow-up, 44 out of the 52 patients underwent biomechanical evaluation with isokinetic strength measurements of both knees. All data were evaluated separately for men and women and compared for each time interval using the Mann–Whitney U test.

Results

Clinical scores improved significantly over the whole study period (p < 0.05). Male patients demonstrated significantly better scores during the follow-up in the KOOS score (p < 0.05). Isokinetic strength measurements after 48 months revealed a significant strength deficit of the treated knee in all test modes compared to the healthy extremity (p < 0.05). Furthermore, male patients achieved significantly higher strength values compared to female patients (p < 0.05).

Conclusions

ACI is a viable treatment option for full-thickness chondral defects in the knee of both genders. Isokinetic muscle strength measures are significantly worse in women (p < 0.05), but physiological and may play a role for the explanation of gender-specific results after ACI.

Level of evidence

II.     

Short-term effect of kinesiology taping on temperature distribution at the site of application

The aim of the study was to assess skin temperature after short-term kinesiology tape application. Seventy-four healthy volunteers with no history of lower back pain participated in the study. Kinesiology tape was applied in the experimental group, and Matopat Classic adhesive tape was applied in the placebo group. Study participants wore the tape for four consecutive days and were then thermographically analyzed for changes in skin temperature. Examination of skin surface temperature distribution revealed a significantly lower temperature (mean decrease, 1.3°C P = .001 area1, 1.5°C P = .001 area2, 1.6 P = .008 area3) immediately after kinesiology tape the removal. One hour after removal of the tape, a statistically significant increase in temperature was observed over all three areas (mean increase, 0.9°C P = .025 area1, 1.0°C P = .0008 area2, 1.0 P = .011 area3). In group 2, there were no statistically significant temperature changes. Based on the findings, we determined that kinesiology taping may affect skin temperature at the site of application.     

Acute effects of kinesio taping on a 6 s maximal cycling sprint performance

Based on the hypothesis that tactile stimulation affects muscle activation levels, we theorized that taping vastus medialis and vastus lateralis muscles would improve a 6 s sprint cycling performance. Thus, the aim of this study was to determine whether the use of kinesio taping (KT) was helpful in increasing maximal-intensity cycling exercise. Sixteen active healthy subjects were enrolled in a randomized placebo, repeated measures design. All subjects were tested on a cycle ergometer under three conditions: without taping, taping along anterior thigh muscles and sham taping across the same muscle groups. Results showed a significant increase in peak power output and total work after the application compared to the condition with no tape applied (p < 0.05). No significant difference was found between the two modes of application. Our findings indicated that the tactile stimulation of KT applied longitudinally provided positive effects during a sprint cycling performance in healthy and active subjects.     

Effect of water immersion methods on post-exercise recovery from simulated team sport exercise

This study aimed to compare the efficacy of hot/cold contrast water immersion (CWI), cold-water immersion (COLD) and no recovery treatment (control) as post-exercise recovery methods following exhaustive simulated team sports exercise. Repeated sprint ability, strength, muscle soreness and inflammatory markers were measured across the 48-h post-exercise period. Eleven male team-sport athletes completed three 3-day testing trials, each separated by 2 weeks. On day 1, baseline measures of performance (10 m × 20 m sprints and isometric strength of quadriceps, hamstrings and hip flexors) were recorded. Participants then performed 80 min of simulated team sports exercise followed by a 20-m shuttle run test to exhaustion. Upon completion of the exercise, and 24 h later, participants performed one of the post-exercise recovery procedures for 15 min. At 48 h post-exercise, the performance tests were repeated. Blood samples and muscle soreness ratings were taken before and immediately after post-exercise, and at 24 h and 48 h post-exercise. In comparison to the control and CWI treatments, COLD resulted in significantly lower (p < 0.05) muscle soreness ratings, as well as in reduced decrements to isometric leg extension and flexion strength in the 48-h post-exercise period. COLD also facilitated a more rapid return to baseline repeated sprint performances. The only benefit of CWI over control was a significant reduction in muscle soreness 24 h post-exercise. This study demonstrated that COLD following exhaustive simulated team sports exercise offers greater recovery benefits than CWI or control treatments.     

Microfracture technique versus osteochondral autologous transplantation mosaicplasty in patients with articular chondral lesions of the knee: a prospective randomized trial with long-term follow-up

Purpose

To compare long-term functional and radiological outcome following microfracture technique (MF) versus osteochondral autologous transplantation (OAT) mosaicplasty for treating focal chondral lesions of the knee.

Methods

Twenty-five patients (mean age 32.3 years, SD 7.7) with a full-thickness (International Cartilage Repair Society grade 3 or 4) chondral lesion of the articulating surface of the femur were randomized to either MF (n = 11) or OAT mosaicplasty (n = 14). At a median follow-up of 9.8 years (range 4.9–11.4), the patients were evaluated using Lysholm score (n = 25), Knee Injury and Osteoarthritis Outcome Score (KOOS, n = 25), isokinetic quadriceps measurement and hamstring strength measurement (n = 22) and standing radiographs (n = 23).

Results

There were no significant differences in Lysholm score, KOOS, isokinetic muscle strength or radiographic osteoarthritis between MF-treated patients and OAT mosaicplasty-treated patients at follow-up. Mean Lysholm score at follow-up was 69.7 [95 % confidence interval (CI), 55.1–84.4] for the MF group and 62.6 (95 % CI, 52.6–72.6) for the OAT mosaicplasty group.

Conclusion

At long-term follow-up, there were no significant differences between patients treated with MF and patients treated with OAT mosaicplasty in patient-reported outcomes, muscle strength or radiological outcome.

Level of evidence

Therapeutic study, Level II.     

Wearing a sports compression garment on the performance of visuomotor tracking following eccentric exercise: A pilot study

Clinical compression garments have been shown to improve functional control in patients with motor impairments, however, investigation in functional control has not been observed whilst wearing sports compression garments. This pilot study assessed motor control changes in the bicep brachii muscle following a bout of eccentric exercise designed to induce delayed onset muscle soreness for intervals up to 14 days after exercise. Eight male participants performed 35 maximal isokinetic eccentric extensions at 90° s^?1. Participants where then randomly divided into one of two groups to perform a one-dimensional elbow flexion/extension visuomotor tracking task; one group wore a sports compression garment during the task, the other acted as control (no garment). The group who wore the compression garment performed the tracking task significantly better immediately post-exercise, and at days 1, 2 and 3 post-exercise (p ≤ 0.05). Non-significant but large and moderate effects sizes (ES), in tracking, were found between the two groups on day 5 (ES = 1.3) and day 7 (ES = 0.7), respectively. Further research is necessary to elucidate these preliminary findings, however, the results suggest that the wearing of sports compression garments post-eccentric exercise has a positive effect on functional motor control.     

Protective effect by maximal isometric contractions against maximal eccentric exercise-induced muscle damage of the knee extensors

This study investigated whether maximal voluntary isometric contractions (MVIC) performed before maximal eccentric contractions (MaxEC) would attenuate muscle damage of the knee extensors. Untrained men were placed to an experimental group that performed 6 sets of 10 MVIC at 90° knee flexion 2 weeks before 6 sets of 10 MaxEC or a control group that performed MaxEC only (n = 13/group). Changes in muscle damage markers were assessed before to 5 days after each exercise. Small but significant changes in maximal voluntary concentric contraction torque, range of motion (ROM) and plasma creatine kinase (CK) activity were evident at immediately to 2 days post-MVIC (p < 0.05), but other variables (e.g. thigh girth, myoglobin concentration, B-mode echo intensity) did not change significantly. Changes in all variables after MaxEC were smaller (p < 0.05) by 45% (soreness)–67% (CK) for the experimental than the control group. These results suggest that MVIC conferred potent protective effect against MaxEC-induced muscle damage.     

Anti-inflammatory doses of ibuprofen: effect on neutrophils and exercise-induced muscle injury

The purpose of the study was to determine the effect of anti-inflammatory doses of ibuprofen on neutrophils, neutrophil O2* production, and markers of muscle injury. Males (n=10) performed 2 bouts of one-arm eccentric exercise on opposite arms separated by three weeks. Subjects received 2400 mg x d(-1) of ibuprofen or a placebo 5 d before exercise and during 10 d of recovery. Measurements were made before the treatments, pre-exercise, at 4 h, and at 1, 2, 3, 4 and 10 d post-exercise. Circulating neutrophil counts were similar between the treatments at the sampling points. Neutrophil counts were higher (p<0.05) for ibuprofen and were elevated (p<0.05) at 4h post-exercise relative to pre-exercise in both treatments. Stimulated neutrophil O2* production was lower for ibuprofen relative to placebo at pre-exercise and was increased (p<0.05) at 4 h and 4 d of both treatments. CK activity at 3 d post-exercise was lower (p<0.05) for ibuprofen relative to placebo. Isometric strength, soreness, tenderness, and arm angles were similar between the treatments. In conclusion, anti-inflammatory doses of ibuprofen reduced CK activity but not the neutrophil response or other indirect markers of muscle injury during recovery from eccentric arm exercise.     

Low-intensity elbow flexion eccentric contractions attenuate maximal eccentric exercise-induced muscle damage of the contralateral arm

Objectives

The magnitude of muscle damage induced by maximal eccentric contractions (MaxEC) of the elbow flexors (EF) is reduced when it is preceded by low-intensity (10% of maximal voluntary isometric contraction strength) eccentric contractions (10%EC) of the same muscle, or by MaxEC of the opposite EF. This study investigated whether 10%EC would reduce the magnitude of muscle damage after MaxEC performed by the opposite arm.

Return to sport: Does excellent 6-month strength and function following ACL reconstruction predict midterm outcomes?

Purpose

The purpose of this study was to determine whether patients with excellent 6-month functional testing after ACL reconstruction had (1) higher risk of subsequent ACL tears, (2) superior knee function, and (3) increased activity levels compared to those with delayed clearance for return to sports at midterm follow-up.

Methods

A total of 223 patients underwent primary ACL reconstruction by a single surgeon and had functional and isokinetic testing performed 6 months post-operatively between 1998 and 2005. Of the 223 patients, 52 (23 %) made the excellent group and were allowed return to sport at 6 months, and the remaining 171 (77 %) constituted the delayed group. Rate of ACL graft tear and native contralateral ACL tear was compared between groups. In addition, IKDC and Tegner scores were compared at a mean 4-year follow-up.

Results

The graft rupture rate was similar in the excellent group (3.8 %, n = 2) compared to the delayed group (4.7 %, n = 8; p = 0.30). However, there was a higher rate of contralateral ACL tear in the excellent group (15.4 %, n = 8 vs. 5.3 %, n = 9; p = 0.003). The excellent 6-month group had superior IKDC scores (94.3 ± 6.4 vs. 90.9 ± 9.7; p = 0.04) and Tegner scores (6.6 ± 1.8 vs. 5.7 ± 1.6; p = 0.01).

Conclusion

Patients with an excellent performance on their isokinetic strength and functional testing at 6 months after ACL reconstruction have superior knee function and higher activity levels at midterm follow-up. However, these patients appear to be at greater risk of contralateral ACL injury, which may be related to their increased activity level. When isokinetic and functional testing is used for return-to-sport decisions, physicians should caution patients about the risk of contralateral ACL injury for high performing patients.

Level of evidence

Retrospective Review with Control, Level III.