Maximal oxygen consumption and energy cost of running after a long-lasting running race: the 100 km of Sahara

The purpose of this study was to investigate the effects of a 120 km desert running race (5 stages over 4 days) on the main physiologic parameters related to the individual aerobic work capacity. Incremental treadmill tests were carried out on 7 recreational long-distance runners (age: 50.4±11.8 years; body mass: 76.0±8.5 kg; mean±SD) before and 3–5 days after the competition. Maximal oxygen consumption (), ventilatory threshold and heart rate were obtained by standard methods; the mean energy cost of running (Cr) above resting was calculated during the same protocol from the slope of the oxygen consumption versus running speed. After the race, the subjects exhibited significant (p<0.05) reductions only in (averaging 7%; from 46.7±5.1 to 43.2±4.4 ml · kg⁻¹ · mm⁻¹) and in maximal heart rate (averaging 3%; from 172.4±14.1 to 166.7±14.5 beats · min⁻¹). Knowledge of Cr (3.78±0.31 J · kg⁻¹ · m⁻¹ and 3.74±0.48 J · kg⁻¹ · m⁻¹, before and after the race respectively) allowed us to estimate the overall daily energy requirement, about 20 850 kJ. and the maximal heart rate seem to be the main variables affected by prolonged strenuous runs followed by insufficient rest periods.     

The biomechanics of running in athletes with previous hamstring injury: A case‐control study

Hamstring injury is prevalent with persistently high reinjury rates. We aim to inform hamstring rehabilitation by exploring the electromyographic and kinematic characteristics of running in athletes with previous hamstring injury. Nine elite male Gaelic games athletes who had returned to sport after hamstring injury and eight closely matched controls sprinted while lower limb kinematics and muscle activity of the previously injured biceps femoris, bilateral gluteus maximus, lumbar erector spinae, rectus femoris, and external oblique were recorded. Intergroup comparisons of muscle activation ratios and kinematics were performed. Previously injured athletes demonstrated significantly reduced biceps femoris muscle activation ratios with respect to ipsilateral gluteus maximus (maximum difference ?12.5%, P = 0.03), ipsilateral erector spinae (maximum difference ?12.5%, P = 0.01), ipsilateral external oblique (maximum difference ?23%, P = 0.01), and contralateral rectus femoris (maximum difference ?22%, P = 0.02) in the late swing phase. We also detected sagittal asymmetry in hip flexion (maximum 8°, P = 0.01), pelvic tilt (maximum 4°, P = 0.02), and medial rotation of the knee (maximum 6°, P = 0.03) effectively putting the hamstrings in a lengthened position just before heel strike. Previous hamstring injury is associated with altered biceps femoris associated muscle activity and potentially injurious kinematics. These deficits should be considered and addressed during rehabilitation.     

ProjectRun21: Do running experience and running pace influence the risk of running injury—A 14-week prospective cohort study

Objectives

The health benefits from participation in half-marathon is challenged by a yearly running-related injury (RRI) incidence proportion exceeding 30%. Research in injury etiology is needed to successfully prevent injuries. The body’s load capacity is believed to play an essential role for injury development. Therefore, the purpose of ProjectRun21 was to investigate the association between load capacity defined as running experience and running pace, and RRI when following a specific half-marathon running schedule.

Running with injury: A study of UK novice and recreational runners and factors associated with running related injury

Objectives

To investigate the incidence and type of running related injuries in novice and recreational UK runners, and identify factors associated with injury.

Investigation of treadmill and overground running: Implications for the measurement of oxygen cost in children with developmental coordination disorder

Differences in the kinematics and kinetics of overground running have been reported between boys with and without developmental coordination disorder (DCD). This study compared the kinematics of overground and treadmill running in children with and without DCD to determine whether any differences in technique are maintained, as this may influence the outcome of laboratory treadmill studies of running economy in this population. Nine boys with DCD (10.3 ± 1.1 year) and 10 typically developing (TD) controls (9.7 ± 1 year) ran on a treadmill and overground at a matched velocity (8.8 ± 0.9 km/h). Kinematic data of the trunk and lower limb were obtained for both conditions using a 12-camera Vicon MX system. Both groups displayed an increase in stance time (p < 0.001), shorter stride length (p < 0.001), higher cadence (p < 0.001) and reduced ankle plantar flexion immediately after toe-off (p < 0.05) when running on the treadmill compared with overground. The DCD group had longer stance time (p < 0.009) and decreased knee flexion at mid-swing (p = 0.04) while running overground compared to their peers, but these differences were maintained when running on the treadmill. Treadmill running improved ankle joint symmetry in the DCD group compared with running overground (p = 0.019). Overall, these findings suggest that there are limited differences in joint kinematics and lower limb symmetry between overground and treadmill running in this population. Accordingly, laboratory studies of treadmill running in children with DCD are likely representative of the energy demands of running.     

Risk factors for lower extremity injuries among half marathon and marathon runners of the Lage Landen Marathon Eindhoven 2012: A prospective cohort study in the Netherlands

To determine risk factors for running injuries during the Lage Landen Marathon Eindhoven 2012. Prospective cohort study. Population‐based study. This study included 943 runners. Running injuries after the Lage Landen Marathon. Sociodemographic and training‐related factors as well as lifestyle factors were considered as potential risk factors and assessed in a questionnaire 1 month before the running event. The association between potential risk factors and injuries was determined, per running distance separately, using univariate and multivariate logistic regression analysis. In total, 154 respondents sustained a running injury. Among the marathon runners, in the univariate model, body mass index ≥ 26 kg/m², ≤ 5 years of running experience, and often performing interval training, were significantly associated with running injuries, whereas in the multivariate model only ≤ 5 years of running experience and not performing interval training on a regular basis were significantly associated with running injuries. Among marathon runners, no multivariate model could be created because of the low number of injuries and participants. This study indicates that interval training on a regular basis may be recommended to marathon runners to reduce the risk of injury.     

A review of research on the mechanical stiffness in running and jumping: methodology and implications

Mechanical stiffness (vertical, leg and joint stiffness) can be calculated during normal human movements, such as running and hopping. Mechanical stiffness is thought to influence several athletic variables, including rate of force development, elastic energy storage and utilization and sprint kinematics. Consequently, the relationship between mechanical stiffness and athletic performance is of great interest to the sport and research communities. Unfortunately, these relationships are relatively unexplored by researchers. For example, there are no longitudinal studies that have investigated the effects of strength or power training on mechanical stiffness levels (calculated during human running). In addition to reviewing the available literature on the relationships between mechanical stiffness (calculated during human running) and functional performance, this review focuses its discussion on the various equipment and methods used to calculate leg-spring stiffness during human running. Furthermore, future implications are presented for practitioners and researchers based on both the limitations and the gaps in the literature reviewed. It is our hope that a better understanding of mechanical stiffness will aid in improving the methodological quality of research in this area and its subsequent effect on athletic performance.     

The energetic cost of gait retraining: A pilot study of the acute effect

ObjectiveTo investigate the acute effect of gait retraining aimed at reducing tibial peak positive acceleration (PPA) on energetic cost (VO₂).DesignIntervention with a pre/post-test design.SettingUniversity biomechanics laboratory.Participants12 healthy male runners (23.4 ± 5.3 years, 179.7 ± 4.3 cm, 75.6 ± 9.2 kg).Main outcome measuresTibial PPA and oxygen consumption (VO₂) were measured after a five minute baseline run and at the end of a gait retraining session aimed at minimizing tibial PPA.ResultsTibial PPA significantly decreased between baseline and after gait retraining (32.6%, p = 0.007). VO₂ significantly increased between the two time periods (9.3%, p = 0.008). There was no correlation between change in tibial PPA and change in VO₂ (p = 0.956, r = 0.018).ConclusionPractitioners who aim to reduce injury risk by minimizing tibial PPA in runners need to consider the possible acute effect on performance as a result of changes in VO₂. Further investigation is warranted to understand the energetic cost of different kinematic strategies used by individuals.     

Comparing the effects of adapting to a weight on one leg during treadmill and overground walking: A pilot study

BackgroundLocomotor adaptation has been suggested as a way to improve gait symmetry in individuals post-stroke. Most perturbation methods utilize costly, specialized equipment. The use of a unilateral leg weight may provide a low cost, clinically translatable alternative. Furthermore, previous studies have suggested that adaptation context may affect movement outcomes. The purpose of this study was to assess the ability of a unilaterally applied ankle weight to drive locomotor adaptation and determine the effect of context (treadmill versus overground) in young, non-disabled participants.MethodsEighteen young non-disabled adults were randomly assigned to receive 10 min of walking on a treadmill with a weight (TG), overground with a weight (OG) or as a control on a treadmill/overground without a weight (CG). Outcomes measured before, during and after adaptation were: step length symmetry, single limb support symmetry and gait speed.ResultsAfter adding the weight, single limb support immediately became asymmetrical for all participants without changes in step length symmetry. After walking for 10 min, TG step length became asymmetrical. After weight removal, both TG and OG had increased step length asymmetry. TG decreased single limb support asymmetry while OG did not. After walking overground without the weight, walking parameters eventually returned to baseline in both weighted groups. The control group showed no changes.ConclusionA unilaterally applied ankle weight appears able to cause gait adaptation in young, non-disabled participants. However different adaptive changes in the gait pattern are made by the nervous system when the perturbation is applied in different contexts.     

Effects of varus knee alignment on gait biomechanics and lower limb muscle activity in boys: A cross sectional study

BackgroundThere is evidence that frontal plane lower limb malalignment (e.g., genu varus) is a risk factor for knee osteoarthritis development. However, only scarce information is available on gait biomechanics and muscle activity in boys with genu varus.Research questionTo examine the effects of knee varus alignment on lower limb kinematics, kinetics and muscular activity during walking at self-selected speed in boys with genu varus versus healthy age-matched controls.MethodsThirty-six boys were enrolled in this study and divided into a group of boys with genu varus (n = 18; age: 11.66 ± 1.64 years) and healthy controls (n = 18; age: 11.44 ± 1.78 years). Three-dimensional kinematics, ground reaction forces, loading rates, impulses and free moments of both limbs were recorded during five walking trials at self-selected speed. Surface electromyography was recorded for rectus femoris and vastus lateralis/medialis muscles.ResultsNo significant between-group differences were found for gait speed. Participants in the genu varus group versus controls showed larger peak knee flexion (p = 0.030; d = 0.77), peak knee adduction (p < 0.001; d = 1.63), and peak ankle eversion angles (p < 0.001; d = 2.06). Significantly higher peak ground reaction forces were found at heel contact (vertical [p = 0.002; d = 1.16] and posterior [p < 0.001; d = 1.63] components) and at push off (vertical [p = 0.010; d = 0.93] and anterior [p < 0.001; d = 1.34] components) for genu varus versus controls. Peak medial ground reaction force (p = 0.032; d = 0.76), vertical loading rate (p < 0.001; d = 1.52), anterior-posterior impulse (p = 0.011; d = 0.92), and peak negative free moment (p = 0.030; d = 0.77) were significantly higher in genu varus. Finally, time to reach peak forces was significantly shorter in genu varus boys compared with healthy controls (p < 0.01; d = 0.73–1.60). The genu varus group showed higher activities in vastus lateralis (p < 0.001; d = 1.82) and vastus medialis (p = 0.013; d = 0.90) during the loading phase of walking.SignificanceOur study revealed genu varus specific gait characteristics and muscle activities. Greater knee adduction angle in genu varus boys may increase the load on the medial compartment of the knee joint. The observed characteristics in lower limb biomechanics and muscle activity could play a role in the early development of knee osteoarthritis in genu varus boys.     

A pilot study on the effects of pre-event manipulation on jump height and running velocity

Purpose

To compare changes in jump height and running velocity with and without pre‐event high‐velocity, low‐amplitude manipulation (HVLA).

Methods

A crossover study design with elite healthy athletes was used. After a 15 min warm‐up, the subjects were tested for countermovement jump height (CMJ) and flying 40 m sprint time (SPRINT). A sport chiropractor then evaluated each subject. Subjects were randomised to either HVLA (applied to joints based on examination) or placebo (simulated performance‐enhancement stickers). They then rested for 60 min, performed another 15 min warm‐up, and were retested. The protocol was repeated 48 h later with the alternative intervention. The mean of two sprints and three jumps were analysed, as well as peak performances. The sample size was based on prior results from the effects of stretching.

Results

19 subjects involved in sprint sports were enrolled; two were too sore to participate on day 2, and one could only participate in the jump (all had HVLA on day 1). Of the 17 participants analysed, seven were female, age range was 19–35, and 17 were national or world‐class athletes. The ranges for baseline measures were: SPRINT 4.1–5.5 s; CMJ 47.4–92.7 cm. Overall, the greater than expected variability in this pilot study led to the study being underpowered. Subjects tended to perform better after HVLA for both CMJ and SPRINT (both mean and peak results), but none of the results were statistically significant (p  =  0.30–0.61).

Conclusion

Although the larger than expected variability in the pilot study means that the observed clinically relevant differences were not statistically significant, the direction and magnitude of the changes associated with HVLA suggest that it may be beneficial. That said, the increased soreness after HVLA suggests that it may be detrimental. HVLA warrants further study.     

Dynamic stability during increased walking speeds is related to balance confidence of older adults: a pilot study

BackgroundSome older individuals walk slower, which may be due to decreases in mechanical stability at faster speeds or due to psychological factors like balance confidence.Research QuestionWhat is the relationship between progressively increasing walking speeds on dynamic stability in older and younger adults and how does this relationship interact with balance confidence in older adults?Methods10 young adults and 14 older adults were recruited for this pilot study. Individuals completed the Activities Specific Balance Confidence Scale. Individuals walked on a treadmill in a robotic device that interfaced with individuals at the pelvis allowing all degrees of freedom of movement and provided safety for a loss of balance. Participants walked at speeds from 0.4 - 2.0m/s in 0.2m/s increments or until the participant chose not to attempt a faster speed. Margin of stability was assessed.ResultsThe ABC of older adults was lower than younger adults (89±13 vs 99±1 scores, p=0.006) and some older adults chose to stop walking before 2.0m/s (n=6). The margin of stability variability of the older adults was significantly greater than young adults in the sagittal (p=0.013) and frontal plane (p=0.007). Older adults became unstable (margin of stability<0) at a slower speed (p<0.001). For older adults, balance confidence was correlated to the fastest speed attempted on the treadmill (rho=0.85, p<0.001). However, the balance confidence and walking speed individuals became unstable were not significantly correlated. Finally, a significant relationship was found between the zero crossing and the fastest speed attempted (rho=0.60, p=0.022).SignificanceSome older adults with lower balance confidence were less willing to experience instability at faster walking speeds on the treadmill, even though the external threat to balance was low. Lower balance confidence and a sense of loss of stability may be factors in decreased willingness to experience activities for some older adults.     

Evidence of knee extensor dysfunction during sit-to-stand following distal femoral extension osteotomy and patellar tendon advancement in young adults with cerebral palsy: A pilot study

A distal femoral extension osteotomy with patellar tendon advancement (DFEO + PTA) is a common treatment for individuals with cerebral palsy (CP) who walk in crouch. Musculoskeletal modeling suggests that the typical patella baja position post-DFEO + PTA may limit one’s abilities to perform sit-to-stand (STS) tasks; however, STS function has not been assessed. Our purpose was to compare how well individuals who received a DFEO + PTA can perform a 5-times STS test (FTSST) eight or more years after surgery compared to their peers who did not receive a DFEO + PTA (non-DFEO + PTA group).Twenty-one participants completed the task (12 DFEO + PTA, 9 non-DFEO + PTA). Three-dimensional kinematics and kinetics were captured. Kinetics were non-dimensionalized to facilitate group comparisons.Non-DFEO + PTA participants performed the FTSST moderately faster than the DFEO + PTA group (median(IQR), 14.6(9.3) seconds vs. 20.3(10.1) seconds, non-parametric effect size ɣ = 0.97, p = 0.241). Peak negative knee power was larger for the non-DFEO + PTA group (Mean ± SD, −0.063 ± 0.025 vs. −0.048± 0.020, Cohen’s d = 0.66, p = 0.165). A similar but weaker trend was observed for negative hip power (median(IQR) −0.120(0.066) vs. −0.105(0.044), ɣ = 0.43, p = 0.671). Both groups used their hips approximately twice as much as their knees to perform the task.The functional deficit among DFEO + PTA participants may be due to patella baja decreasing the knee extensor moment arm, which concurs with the modeling prediction. The group differences may also be due to the non-DFEO + PTA group being slightly higher functioning. Future research is warranted to determine if optimizing patella position during a DFEO + PTA may improve unaided STS function without compromising gait improvements.     

A randomised clinical trial of the efficacy of drop squats or leg extension/leg curl exercises to treat clinically diagnosed jumper's knee in athletes: pilot study

OBJECTIVES: To compare the therapeutic effect of two different exercise protocols in athletes with jumper's knee. METHODS: Randomised clinical trial comparing a 12 week programme of either drop squat exercises or leg extension/leg curl exercises. Measurement was performed at baseline and after six and 12 weeks. Primary outcome measures were pain (visual analogue scale 1-10) and return to sport. Secondary outcome measures included quadriceps and hamstring moment of force using a Cybex II isokinetic dynamometer at 30 degrees/second. Differences in pain response between the drop squat and leg extension/curl treatment groups were assessed by 2 (group) x 3 (time) analysis of variance. Two by two contingency tables were used to test differences in rates of return to sport. Analysis of variance (2 (injured versus non-injured leg) x 2 (group) x 3 (time)) was also used to determine differences for secondary outcome measures. RESULTS: Over the 12 week intervention, pain diminished by 2.3 points (36%) in the leg extension/curl group and 3.2 points (57%) in the squat group. There was a significant main effect of both exercise protocols on pain (p<0.01) with no interaction effect. Nine of 10 subjects in the drop squat group returned to sporting activity by 12 weeks, but five of those subjects still had low level pain. Six of nine of the leg extension/curl group returned to sporting activity by 12 weeks and four patients had low level pain. There was no significant difference between groups in numbers returning to sporting activity. There were no differences in the change in quadriceps or hamstring muscle moment of force between groups. CONCLUSIONS: Progressive drop squats and leg extension/curl exercises can reduce the pain of jumper's knee in a 12 week period and permit a high proportion of patients to return to sport. Not all patients, however, return to sport by that time.     

A comparison of the spatiotemporal parameters, kinematics, and biomechanics between shod, unshod, and minimally supported running as compared to walking

Recreational running has many proven benefits which include increased cardiovascular, physical and mental health. It is no surprise that Running USA reported over 10 million individuals completed running road races in 2009 not to mention recreational joggers who do not wish to compete in organized events. Unfortunately there are numerous risks associated with running, the most common being musculoskeletal injuries attributed to incorrect shoe choice, training errors and excessive shoe wear or other biomechanical factors associated with ground reaction forces. Approximately 65% of chronic injuries in distance runners are related to routine high mileage, rapid increases in mileage, increased intensity, hills or irregular surface running, and surface firmness. Humans have been running barefooted or wearing minimally supportive footwear such as moccasins or sandals since the beginning of time while modernized running shoes were not invented until the 1970s. However, the current trend is that many runners are moving back to barefoot running or running in “minimal” shoes. The goal of this masterclass article is to examine the similarities and differences between shod and unshod (barefoot or minimally supportive running shoes) runners by examining spatiotemporal parameters, energetics, and biomechanics. These running parameters will be compared and contrasted with walking. The most obvious difference between the walking and running gait cycle is the elimination of the double limb support phase of walking gait in exchange for a float (no limb support) phase. The biggest difference between barefoot and shod runners is at the initial contact phase of gait where the barefoot and minimally supported runner initiates contact with their forefoot or midfoot instead of the rearfoot. As movement science experts, physical therapists are often called upon to assess the gait of a running athlete, their choice of footwear, and training regime. With a clearer understanding of running and its complexities, the physical therapist will be able to better identify faults and create informed treatment plans while rehabilitating patients who are experiencing musculoskeletal injuries due to running.     

Is range of motion of the hip and ankle joint related to running injuries? A case control study.

This study concerns a case-control study on the relation between range of motion (ROM) of the hip and ankle joints and running injuries. Sixteen male runners who had sustained a medically treated running injury during the year prior to the ROM measurements were matched for weekly running distance and age with sixteen male runners who had not sustained such an injury. All subjects were fit at the time of measurement. ROM was measured by standardized goniometry after a warm-up on a cycle-ergometer. Within non-injured subjects all goniometric measurements showed no significant (p > 0.05) differences between the left and right side of the body. Within injured subjects all goniometric measurements showed no significant (p > 0.05) differences between the injured and non-injured side of the body. Runners who had sustained a running injury showed a significant (p > 0.001) more restricted ROM of the hip joints (average ROM value 59.4 degrees +/- 8.0 degrees) in comparison to runners who had no been injured during the same period (average value ROM 68.1 degrees +/- 5.2 degrees). No such differences (p > 0.05) were found with regard to ankle ROM (average ROM value injured 12.8 degrees +/- 3.4 degrees and average ROM value non injured 14.0 degrees +/- 2.7 degrees). These findings suggest that ROM can be characterized as a more or less stable anthropometric trait.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of exercise on key pharmacokinetic parameters related to metformin absorption in healthy humans: A pilot study

Exercise is widely accepted as having therapeutic effects; thus, it is important to know whether it interacts with medications. The aim of the present pilot study was to examine the effect of high-intensity interval exercise (known to have antidiabetic action) on key pharmacokinetic parameters related to absorption of metformin (the first-line medication against type 2 diabetes). Ten healthy men participated in two sessions, spaced one to two weeks apart in random, counterbalanced order. In both sessions, participants received 1000 mg of metformin orally, 1-1.5 hours after breakfast. Then, they either ran for 60 minutes at alternating intensity, starting at 40 minutes after metformin administration, and rested without food consumption over the next 3 hours or they rested without food consumption during the entire testing period. Venous blood samples were collected before and at 0.5, 2, 2.5, 3, 3.5, 4, and 4.5 hours after metformin administration for metformin determination by liquid chromatography-mass spectrometry. Capillary blood samples were also collected for lactate and glucose measurements. Data from the two sessions were compared through Wilcoxon or Student's t test, as appropriate. Maximum plasma concentration of metformin (C_max) was higher at exercise compared to rest (P = .059). Time to reach C_max (T_max) decreased with exercise (P = .009), and the area under the metformin concentration vs time curve was higher at exercise (P = .047). The addition of exercise to metformin administration did not cause hypoglycemia or lactic acidosis. In conclusion, our results provide the first evidence that pharmacokinetic values related to metformin absorption are affected by exercise.     

Simulated games activity vs continuous running exercise: A novel comparison of the glycemic and metabolic responses in T1DM patients

To compare the glycemic and metabolic responses to simulated intermittent games activity and continuous running exercise in type 1 diabetes. Nine patients (seven male, two female; 35 ± 4 years; HbA1c 8.1 ± 0.2%/65 ± 2 mmol/mol) treated on a basal‐bolus regimen completed two main trials, a continuous treadmill run (CON) or an intermittent running protocol (INT). Patients arrived to the laboratory fasted at ～ 08:00 h, replicating their usual pre‐exercise meal and administering a 50% reduced dose of rapid‐acting insulin before exercising. Blood glucose (BG), K⁺, Na⁺⁺, pH, triglycerides, serum cortisol and NEFA were measured at baseline and for 60 min post‐exercise. Interstitial glucose was measured for a further 23 h under free‐living conditions. Following exercise, BG declined under both conditions but was less under INT (INT ?1.1 ± 1.4 vs CON ?5.3 ± 0.4 mmol/L, P = 0.037), meaning more patients experienced hypoglycemia (BG ≤ 3.5 mmol/L; CON n = 3 vs INT n = 2) but less hyperglycemia (BG ≥ 10.9 mmol/L; CON n = 0 vs INT n = 6) under CON. Blood lactate was significantly greater, and pH lower, with a temporal delay in K⁺ under INT (P < 0.05). No conditional differences were observed in other measures during this time, or in interstitial glucose concentrations during the remaining 23 h after exercise. Simulated games activity carries a lower risk of early, but not late‐onset hypoglycemia than continuous running exercise in type 1 diabetes.