Effects of cold water immersion on knee joint position sense in healthy volunteers

The purpose of this study was to determine the effects of cryotherapy, in the form of cold water immersion, on knee joint position sense. Fourteen healthy volunteers, with no previous knee injury or pre-existing clinical condition, participated in this randomized cross-over trial. The intervention consisted of a 30-min immersion, to the level of the umbilicus, in either cold (14 ± 1 °C) or tepid water (28 ± 1 °C). Approximately one week later, in a randomized fashion, the volunteers completed the remaining immersion. Active ipsilateral limb repositioning sense of the right knee was measured, using weight-bearing and non-weight-bearing assessments, employing video-recorded 3D motion analysis. These assessments were conducted immediately before and after a cold and tepid water immersion. No significant differences were found between treatments for the absolute (P = 0.29), relative (P = 0.21) or variable error (P = 0.86). The average effect size of the outcome measures was modest (range -0.49 to 0.9) and all the associated 95% confidence intervals for these effect sizes crossed zero. These results indicate that there is no evidence of an enhanced risk of injury, following a return to sporting activity, after cold water immersion.     

Effect of water ingestion on endurance capacity during prolonged running

This study examined the influence of water ingestion on endurance capacity during submaximal treadmill running. Four men and four women with a mean (± S.E.) age of 21.4 ± 0.7 years, height of 169 + 2 cm, body mass of 63.1 ± 2.9 kg and VO ₂ max of 51.1 ± 1.8 ml kg^?1 min^?1, performed two randomly assigned treadmill runs at 70% VO ₂ max to exhaustion. No fluid was ingested during one trial (NF‐trial), whereas a single water bolus of 3.0 ml kg^?1 body mass was ingested immediately pre‐exercise and serial feedings of 2.0 ml kg^?1 body mass were ingested every 15 min during exercise in a fluid replacement trial (FR‐trial). Run time for the NF‐trial was 77.7 ± 7.7 min, compared to 103 ± 12.4 min for the FR‐trial (P<0.01). Body mass (corrected for water ingestion) decreased by 2.0 ± 0.2% in the NF‐trial and 2.7 ± 0.2% in the FR‐trial (P<0.01), while plasma volume decreased by 1.1 ± 1.1% and 3.5 ± 1.1% in the two trials respectively (N.S.). However, these apparent differences in circulatory volume were not associated with differences in rectal temperature. Respiratory exchange ratios indicated increased carbohydrate metabolism (73% vs 64% of total energy expenditure) and suppressed fat metabolism after 75 min of exercise in the NF‐trial compared with the FR‐trial (NF‐trial, 0.90 ± 0.01; FR‐trial, 0.86 ± 0.03; P<0.01). Blood glucose concentrations were similar in both trials, while blood lactate concentrations were higher in the NF‐trial at the end of exercise (4.83 ± 0.34 vs 4.18 ± 0.38 mM; P<0.05). In summary, water ingestion during prolonged running improved endurance capacity.     

Acceleration patterns in the lower and upper trunk during running

Abstract

The purpose of the present study was to relate 3D acceleration patterns of the lower and upper trunk during running to running gait cycle, assess the validity of stride duration estimated from acceleration patterns, investigate speed-dependent changes in acceleration, and examine the test–retest reliability of these parameters. Thirteen healthy young men performed two running trials each on a treadmill and on land at three speeds (slow, preferred, and fast). The 3D accelerations were measured at the L3 spinous process (lower trunk) and the ensiform process (upper trunk) and synchronised with digital video data. The amplitude and root mean square of acceleration and stride duration were calculated and then analysed by three-way analysis of variance to test effects of running conditions, device location, and running speed. Bland-Altman analysis was used to evaluate the test–retest reliability. Marked changes in acceleration were observed in relation to foot strike during running. Stride durations calculated from the vertical accelerations were nearly equal to those estimated from video data. There were significant speed effects on all parameters, and the low test–retest reliability was confirmed in the anterior–posterior acceleration during treadmill running and the anterior–posterior acceleration at slow speed during treadmill and overground running.     

Influence of shoe drop on running kinematics and kinetics in female runners

Abstract

This study investigated the effects of shoe drop on lower limb kinematics and kinetics in female runners.

Fifteen healthy female runners ran on a 15-m runway at their preferred speed with three different shoe-drop conditions: 0 (D₀), 6 (D₆) and 10 (D₁₀) mm. Three-dimensional marker positions and ground reaction forces were recorded to analyse kinetic and kinematic parameters using zero- (0D) and one-dimensional (1D) metrics (statistical parametric mapping, SPM). Regarding 0D parameters, significantly higher loading rates and transient peaks were found in D₀ compared to D₆ and D₁₀ conditions (both p?<?.01). For 1D analysis, significantly higher ankle dorsiflexion moments were found in D₀ compared to D₆ and D₁₀ during the braking phase (p?<?.01). Lower knee extension moments between 52% and 55% and 61% and 65% of contact time (p?<?.05) were also found. No difference was found between D₆ and D₁₀ conditions (p?>?.05). As previously shown in men, this study demonstrates that shoe drop influences running kinematic and kinetic patterns. Using SPM analysis in conjunction with classical analysis, the study adds new understanding on the influence of shoes on joint moment during contact time.     

增强髋关节力量的重要性——优秀女子短跑运动员秦旺萍的训练启示

以当代短跑训练理论为指导,运用文献资料、个案研究、实验等方法对江苏省女子优秀短跑运动员秦旺萍进行增强髋关节力量训练的跟踪研究。研究认为增强髋关节力量(尤其是伸髋力量)对优秀短跑运动员具有十分重要的意义,它是当代优秀短跑选手以髋为轴高速摆动技术的重要保证,在短跑力量训练中应引起足够的重视。     

Effects of mild running on substantia nigra during early neurodegeneration

Moderate physical exercise acts at molecular and behavioural levels, such as interfering in neuroplasticity, cell death, neurogenesis, cognition and motor functions. Therefore, the aim of this study is to analyse the cellular effects of moderate treadmill running upon substantia nigra during early neurodegeneration. Aged male Lewis rats (9-month-old) were exposed to rotenone 1mg/kg/day (8 weeks) and 6 weeks of moderate treadmill running, beginning 4 weeks after rotenone exposure. Substantia nigra was extracted and submitted to proteasome and antioxidant enzymes activities, hydrogen peroxide levels and Western blot to evaluate tyrosine hydroxylase (TH), alpha-synuclein, Tom-20, PINK1, TrkB, SLP1, CRMP-2, Rab-27b, LC3II and Beclin-1 level. It was demonstrated that moderate treadmill running, practiced during early neurodegeneration, prevented the increase of alpha-synuclein and maintained the levels of TH unaltered in substantia nigra of aged rats. Physical exercise also stimulated autophagy and prevented impairment of mitophagy, but decreased proteasome activity in rotenone-exposed aged rats. Physical activity also prevented H₂O₂ increase during early neurodegeneration, although the involved mechanism remains to be elucidated. TrkB levels and its anterograde trafficking seem not to be influenced by moderate treadmill running. In conclusion, moderate physical training could prevent early neurodegeneration in substantia nigra through the improvement of autophagy and mitophagy.     

Effects of footwear midsole thickness on running biomechanics

Shoe manufacturers launch running shoes with increased (e.g., maximalists) or decreased (e.g., minimalists) midsole thickness and claim that they may prevent running injury. Previous studies tested footwear models with different midsole thicknesses on the market but the shoe construct was not strictly comparable. Therefore, in the present study, we examined the effect of midsole thickness, from 1-mm to 29-mm, in a standard test shoe prototype on the vertical loading rates, footstrike angle and temporal spatial parameters in distance runners. Fifteen male habitual rearfoot strikers were recruited from local running clubs. They were asked to run on an instrumented treadmill in shoes with different midsole thicknesses. We found significant interactions between midsole thickness with vertical loading rates (p < 0.001), footstrike angle (p = 0.013), contact time (p < 0.001), cadence (p = 0.003), and stride length (p = 0.004). Specifically, shoes with thinner midsole (1- and 5-mm) significantly increased the vertical loading rates and shortened the contact time, when compared with thicker midsole shoes (25- and 29-mm). However, we did not observe any substantial differences in the footstrike angle, cadence and stride length between other shod conditions. The present study provides biomechanical data regarding the relationship between full spectrum midsole thicknesses and running biomechanics in a group of rearfoot strikers.     

Independent effects of step length and foot strike pattern on tibiofemoral joint forces during running

The purpose of this study was to examine the effects of step length and foot strike pattern along with their interaction on tibiofemoral joint (TFJ) and medial compartment TFJ kinetics during running. Nineteen participants ran with a rear foot strike pattern at their preferred speed using a short (?10%), preferred, and long (+10%) step length. These step length conditions were then repeated using a forefoot strike pattern. Regardless of foot strike pattern, a 10% shorter step length resulted in decreased peak contact force, force impulse per step, force impulse per kilometre, and average loading rate at the TFJ and medial compartment, while a 10% increased step length had the opposite effects (all P < 0.05). A forefoot strike pattern significantly lowered TFJ and medial compartment TFJ average loading rates compared with a rear foot strike pattern (both <0.05) but did not change TFJ or medial compartment peak force, force impulse per step, or force impulse per km. The combination of a shorter step length and forefoot strike pattern produced the greatest reduction in peak medial compartment contact force (P < 0.05). Knowledge of these running modification effects may be relevant to the management or prevention of TFJ injury or pathology among runners.     

Effects of Altered Stride Lengths on Ratings of Perceived Exertion during Running

Abstract

The purpose of this study was to determine the effects of stride length variations on ratings of perceived exertion (RPEs) in experienced recreational runners. Twenty-eight male college students were randomly divided into equal-sized treatment and control groups. The treatment group performed five 15 min altered stride length runs, each separated by a minimum of 48 hr. The five trials involved running with a freely chosen stride length (FCSL) and a FCSL altered by +14%, +7%, ?14%, and ?7%. The control group was utilized to monitor changes in subjects' RPEs as a result of practice effects developed through repeated bouts of treadmill running. Results revealed that the treatment group's local and general RPEs for the over striding runs (+14%, +7%) were significantly greater (p < .01) than RPEs recorded during the FCSL run. Additionally, there was a marginally significant difference (p < .05) in local RPEs between the FCSL run and the extreme understriding run (?14%). Analysis of variance on the control group's RPE data suggests that neither local nor general RPEs changed significantly in repeated FCSL runs across the six-week testing period. The results of this study suggest that experienced recreational runners perceive differences in exertion accompanying changes in stride length.     

Durability of running shoes with ethylene vinyl acetate or polyurethane midsoles

Abstract

Ethylene vinyl acetate and polyurethane are widely used materials for shoe midsoles. The present study investigated the durability of running shoes made from ethylene vinyl acetate and one type of polyurethane (polyurethane-1), which have similar hardness and density, and another type of polyurethane (polyurethane-2), which has high hardness/density. All shoes differed from one another only in terms of the midsole material used. Eight male runners participated in the present study and used the shoes to run 500 km (10 × 50 km). The cushioning and energy return characteristics of each shoe were measured using an impact tester before and after each 50-km run. The results showed that as the running distance increased, the peak force of midsole materials changed with different patterns. Ethylene vinyl acetate and polyurethane-1 showed greater cushioning than polyurethane-2 over 500 km (ethylene vinyl acetate, 918.2–968.0 N; polyurethane-1, 909.6–972.9 N; polyurethane-2, 983.0–1105.6 N). Polyurethane-1 showed greater cushioning from 200 km to 300 km compared with 0 km (0 km, 972.9 ± 66.3 N; 200 km, 909.6 ± 61.2 N; 250 km, 921.9 ± 51.2 N; 300 km, 924.6 ± 51.9 N). The cushioning of ethylene vinyl acetate shoes was diminished after 500 km compared with that at 0 km (968.0 ± 25.9 N vs. 921.1 ± 20.1 N). Ethylene vinyl acetate resulted in greater energy returns than polyurethane. Both foam category and hardness/density affected the critical biomechanical properties of running shoes.     

Effects of cold water immersion on the symptoms of exercise-induced muscle damage.

Cryotherapy is an effective treatment for acute sports injury to soft tissue, although the effect of cryotherapy on exercise-induced muscle damage is unclear. The aim of this study was to assess the effects of cold water immersion on the symptoms of exercise-induced muscle damage following strenuous eccentric exercise. After performing a bout of damage-inducing eccentric exercise (eight sets of five maximal reciprocal contractions at 0.58 rad x s(-1)) of the elbow flexors on an isokinetic dynamometer, 15 females aged 22.0+/-2.0 years (mean +/- s) were allocated to a control group (no treatment, n = 7) or a cryotherapy group (n = 8). Subjects in the cryotherapy group immersed their exercised arm in cold water (15 degrees C) for 15 min immediately after eccentric exercise and then every 12 h for 15 min for a total of seven sessions. Muscle tenderness, plasma creatine kinase activity, relaxed elbow angle, isometric strength and swelling (upper arm circumference) were measured immediately before and for 3 days after eccentric exercise. Analysis of variance revealed significant (P < 0.05) main effects for time for all variables, with increases in muscle tenderness, creatine kinase activity and upper arm circumference, and decreases in isometric strength and relaxed elbow angle. There were significant interactions (P<0.05) of group x time for relaxed elbow angle and creatine kinase activity. Relaxed elbow angle was greater and creatine kinase activity lower for the cryotherapy group than the controls on days 2 and 3 following the eccentric exercise. We conclude that although cold water immersion may reduce muscle stiffness and the amount of post-exercise damage after strenuous eccentric activity, there appears to be no effect on the perception of tenderness and strength loss, which is characteristic after this form of activity.     

不同极简指数跑鞋对髌股关节受力特征的影响

聚焦跑步时髌股关节生物力学特征,探究穿着不同极简指数(MI)跑鞋对髌股关节接触力、应力等的即刻影响。选取15名习惯后跟着地的健康男性跑者,分别穿着两种MI跑鞋(MI 86%极简跑鞋和MI 26%缓冲跑鞋),使用Vicon红外运动捕捉系统、Kistler三维测力台同步采集3.33 m/s(速度变化范围±5%)跑速下的膝、踝关节运动学和地面反作用力,通过逆向动力学等计算股四头肌肌力、髌股关节接触力、髌股关节接触面积以及髌股关节接触应力。结果显示:两种跑鞋条件下的冲击力峰值和蹬地力峰值均无明显差异。与缓冲跑鞋相比,穿着极简跑鞋跑步时,膝关节最大屈曲角度显著降低(P<0.01);髌股关节接触面积显著减小(P<0.01);膝关节伸肌峰值力矩显著下降(P<0.01);髌股关节接触力和应力峰值均显著减小(P<0.05)。研究表明,相比缓冲跑鞋,穿着极简跑鞋在未影响触地后冲击力峰值的同时,通过降低伸膝力矩大幅度减少髌股关节接触力(下降17.02%)、降低髌股关节接触应力,从而有效改善支撑期髌股关节负荷,为进一步减小髌股关节疼痛综合征风险提供可能。     

对百米途中跑摆动腿摆动技术的生物力学分析

运用生物力学原理，对跑步一个周期中摆动腿的动作阶段进行了划分，对摆动腿在各摆动阶段的动作技术进行了简要的分析，以期为现代短跑途中跑的教学和训练提供理论依据。     

The effect of foot orthoses and insoles on running economy and performance in distance runners: A systematic review and meta-analysis

ABSTRACT

Foot orthoses and insoles are prescribed to runners, however their impact on running economy and performance is uncertain. The aim of this systematic review and meta-analysis was to determine the effect of foot orthoses and insoles on running economy and performance in distance runners. Seven electronic databases were searched from inception until June 2018. Eligible studies investigated the effect of foot orthoses or insoles on running economy (using indirect calorimetry) or running performance. Standardised mean differences (SMDs) were computed and meta-analyses were conducted using random effects models. Methodological quality was assessed using the Quality Index. Nine studies met the criteria and were included: five studies investigated the effect of foot orthoses on running economy and four investigated insoles. Foot orthoses were associated with small negative effects on running economy compared to no orthoses (SMD 0.42 [95% CI 0.17,0.72] p = 0.007). Shock absorbing insoles were also associated with negative effects on running economy, but an imprecise estimate (SMD 0.26 [95% CI ?0.33,0.84] p = 0.83). Quality Index scores ranged from 4 to 15 out of 17. Foot orthoses and shock absorbing insoles may adversely affect running economy in distance runners. Future research should consider their potential effects on running performance.     

The effect of alterations in foot centre of pressure on lower body kinematics during the five-iron golf swing

ABSTRACT

The research aimed to evaluate the effects of an intervention aimed at altering pressure towards the medial aspect of the foot relating to stability mechanisms associated with the golf swing. We hypothesised that by altering the position of the foot pressure, the lower body stabilisation would improve which in turn would enhance weight distribution and underpinning lower body joint kinematics. Eight professional golf association (PGA) golf coaches performed five golf swings, recorded using a nine-camera motion analysis system synchronised with two force platforms. Following verbal intervention, they performed further five swings. One participant returned following a one-year intervention programme and performed five additional golf swings to provide a longitudinal case study analysis. Golf performance was unchanged evidenced by the velocity and angle of the club at ball impact (BI), although the one-year intervention significantly changed the percentage of weight experienced at each foot in the final 9% of downswing, which provided an even weight distribution at BI. This is a highly relevant finding as it indicates that the foot centre of pressure was central to the base of support and in-line with the centre of mass (CoM), indicating significantly increased stability when the CoM is near maximal acceleration.     

Effect of attending to a ball during a side-cut maneuver on lower extremity biomechanics in male and female athletes

Many sports associated with anterior cruciate ligament (ACL) injury require athletes attend to a ball during participation. We investigated effects of attending to a ball on lower extremity mechanics during a side-cut maneuver and if these effects are consistent for males and females. Sagittal and frontal plane hip and knee kinematics and joint moments were measured during side-cut maneuvers in 19 male and 19 female National Collegiate Athletic Association division III basketball players. Participants also experienced two side-cut conditions that required attention to a ball. Our results did not indicate that the effect of attention varies with gender. However, during side-cut conditions while attending to a ball, internal knee adductor moment was 20% greater (p = 0.03) and peak knee flexion angle was 4° larger (p < 0.01). Females demonstrated 5° less hip flexion (p = 0.046), 12° less knee flexion (p < 0.01), and 4° more knee abduction (p = 0.026) at initial contact during all side-cut conditions than males. Attention to a ball may affect lower extremity mechanics relevant to ACL injury. The validity of laboratory studies of lower extremity mechanics for sports that include attention to a ball may be increased if participants are required to attend to a ball during the task.     

Effect of attending to a ball during a side-cut maneuver on lower extremity biomechanics in male and female athletes

Many sports associated with anterior cruciate ligament (ACL) injury require athletes attend to a ball during participation. We investigated effects of attending to a ball on lower extremity mechanics during a side-cut maneuver and if these effects are consistent for males and females. Sagittal and frontal plane hip and knee kinematics and joint moments were measured during side-cut maneuvers in 19 male and 19 female National Collegiate Athletic Association division III basketball players. Participants also experienced two side-cut conditions that required attention to a ball. Our results did not indicate that the effect of attention varies with gender. However, during side-cut conditions while attending to a ball, internal knee adductor moment was 20% greater (p = 0.03) and peak knee flexion angle was 4 degrees larger (p < 0.01). Females demonstrated 5 degrees less hip flexion (p = 0.046), 12 degrees less knee flexion (p < 0.01), and 4 degrees more knee abduction (p = 0.026) at initial contact during all side-cut conditions than males. Attention to a ball may affect lower extremity mechanics relevant to ACL injury. The validity of laboratory studies of lower extremity mechanics for sports that include attention to a ball may be increased if participants are required to attend to a ball during the task.     

Effects of a verbal and visual feedback system on running technique,perceived exertion and running economy in female novice runners

The purpose of this study was to determine the effects of a verbal and visual feedback system on running technique, ratings of perceived exertion (RPE), and running economy. Twenty‐two female novice runners were randomly assigned to experimental (n = 11) and control (n = 11) groups. The experimental subjects received verbal and visual feedback concerning their running technique prior to and during each training run. Training involved 15 20‐min treadmill running sessions over a 5‐week period. The control group adhered to the same training routine but did not receive feedback concerning their running technique. High‐speed (100 Hz) photography was used to collect biomechanical data. A submaximal oxygen consumption test and Borg's RPE scale were used to collect data concerning running economy and perceived exertion, respectively. Statistical analysis using ANCOVA revealed that the proposed feedback system had a significant (P < 0.01) effect on the experimental group's running technique by affecting the following desired changes relative to the control group: greater relative stride lengths, shorter support time, greater ankle dorsiflexion during support and greater knee flexion during support and non‐support. There were no significant differences between the groups in submaximal VO₂ or RPE. The results of this study suggest that verbal and visual feedback are effective means of eliciting modifications in running style in female novice runners. The link between modifications in running style and improvements in running economy and perceived exertion remains unclear.     

Cold-water immersion alters muscle recruitment and balance of basketball players during vertical jump landing

The purpose of this study was to evaluate the effects of cold-water immersion on the electromyographic (EMG) response of the lower limb and balance during unipodal jump landing. The evaluation comprised 40 individuals (20 basketball players and 20 non-athletes). The EMG response in the lateral gastrocnemius, tibialis anterior, fibular longus, rectus femoris, hamstring and gluteus medius; amplitude and mean speed of the centre of pressure, flight time and ground reaction force (GRF) were analysed. All volunteers remained for 20 min with their ankle immersed in cold-water, and were re-evaluated immediately post and after 10, 20 and 30 min of reheating. The Shapiro–Wilk test, Friedman test and Dunn’s post test (P < 0.05) were used. The EMG response values decreased for the lateral gastrocnemius, tibialis anterior, fibular longus and rectus femoris of both athletes and non-athletes (P < 0.05). The comparison between the groups showed that the EMG response was lower for the athletes. Lower jump flight time and GRF, greater amplitude and mean speed of centre of pressure were predominant in the athletes. Cold-water immersion decreased the EMG activity of the lower limb, flight time and GRF and increased the amplitude and mean speed of centre of pressure.     

无痛苦跑对改善大学生跑步恐惧心理的影响

分析了高校传统耐力跑教学导致的学生厌学情绪和恐惧心理,进行了无痛苦跑的教学实验。指出:极点和痛苦并无健康价值,无痛苦跑不是惧怕和回避痛苦,而是另一种积极面对。结果表明,学生对无痛苦跑支持率为69%,学生恐惧心理和厌学情绪得到明显的改善。