Bas Kluitenberg

Comparison of vertical ground reaction forces during overground and treadmill running. A validation study

BackgroundOne major drawback in measuring ground-reaction forces during running is that it is time consuming to get representative ground-reaction force (GRF) values with a traditional force platform. An instrumented force measuring treadmill can overcome the shortcomings inherent to overground testing. The purpose of the current study was to determine the validity of an instrumented force measuring treadmill for measuring vertical ground-reaction force parameters during running.MethodsVertical ground-reaction forces of experienced runners (12 male, 12 female) were obtained during overground and treadmill running at slow, preferred and fast self-selected running speeds. For each runner, 7 mean vertical ground-reaction force parameters of the right leg were calculated based on five successful overground steps and 30 seconds of treadmill running data. Intraclass correlations (ICC(3,1)) and ratio limits of agreement (RLOA) were used for further analysis.ResultsQualitatively, the overground and treadmill ground-reaction force curves for heelstrike runners and non-heelstrike runners were very similar. Quantitatively, the time-related parameters and active peak showed excellent agreement (ICCs between 0.76 and 0.95, RLOA between 5.7% and 15.5%). Impact peak showed modest agreement (ICCs between 0.71 and 0.76, RLOA between 19.9% and 28.8%). The maximal and average loading-rate showed modest to excellent ICCs (between 0.70 and 0.89), but RLOA were higher (between 34.3% and 45.4%).ConclusionsThe results of this study demonstrated that the treadmill is a moderate to highly valid tool for the assessment of vertical ground-reaction forces during running for runners who showed a consistent landing strategy during overground and treadmill running. The high stride-to-stride variance during both overground and treadmill running demonstrates the importance of measuring sufficient steps for representative ground-reaction force values. Therefore, an instrumented treadmill seems to be suitable for measuring representative vertical ground-reaction forces during running.

Differences in kinetic variables between injured and noninjured novice runners: A prospective cohort study

OBJECTIVES This prospective study examined differences in kinetic variables between injured and noninjured novice female and male runners and their potential contribution to RRIs. DESIGN A prospective cohort study. METHODS At baseline vertical ground reaction forces were assessed with an instrumented treadmill equipped with three force measuring transducers. Female participants ran at 8 and 9kmh(-1) and male runners ran at 9 and 10kmh(-1). Primary outcome measure was a running related injury (RRI). Participants were novice female and male recreational runners and were followed during a 9-week running program with three running sessions a week. RESULTS One hundred thirty three female and seventy seven male runners participated in this study. Mean age was 37.2years and the BMI was 23.9kgm(-2). During the nine week running program 16.2% of the participants sustained an injury and no difference in incidence between female and male runners was seen. In injured male runners loading rate was significantly higher compared to noninjured male runners at both running speeds and contact time in the injured male group was significantly shorter at 9kmh(-1). In the group of female injured and noninjured runners no differences on kinetic or spatio-temporal variables were observed. Female runners had significantly higher loading rates compared to male runners but this did not have an effect on the incidence of RRIs. CONCLUSIONS This study showed that male injured runners had higher loading rates and shorter contact times than noninjured male runners. In female runners, however, no differences in kinetic or spatio-temporal variables were observed between injured and noninjured novice runners.

Running with a minimalist shoe increases plantar pressure in the forefoot region of healthy female runners

OBJECTIVES Minimalist running shoes have been proposed as an alternative to barefoot running. However, several studies have reported cases of forefoot stress fractures after switching from standard to minimalist shoes. Therefore, the aim of the current study was to investigate the differences in plantar pressure in the forefoot region between running with a minimalist shoe and running with a standard shoe in healthy female runners during overground running. DESIGN Randomized crossover design. METHODS In-shoe plantar pressure measurements were recorded from eighteen healthy female runners. Peak pressure, maximum mean pressure, pressure time integral and instant of peak pressure were assessed for seven foot areas. Force time integral, stride time, stance time, swing time, shoe comfort and landing type were assessed for both shoe types. A linear mixed model was used to analyze the data. RESULTS Peak pressure and maximum mean pressure were higher in the medial forefoot (respectively 13.5% and 7.46%), central forefoot (respectively 37.5% and 29.2%) and lateral forefoot (respectively 37.9% and 20.4%) for the minimalist shoe condition. Stance time was reduced with 3.81%. No relevant differences in shoe comfort or landing strategy were found. CONCLUSIONS Running with a minimalist shoe increased plantar pressure without a change in landing pattern. This increased pressure in the forefoot region might play a role in the occurrence of metatarsal stress fractures in runners who switched to minimalist shoes and warrants a cautious approach to transitioning to minimalist shoe use.

Differences in kinetic asymmetry between injured and noninjured novice runners: A prospective cohort study

PURPOSE The purpose of this prospective study was to describe natural levels of asymmetry in running, compare levels of asymmetry between injured and noninjured novice runners and compare kinetic variables between the injured and noninjured lower limb within the novice runners with an injury. METHODS At baseline vertical ground reaction forces and symmetry angles (SA) were assessed with an instrumented treadmill equipped with three force measuring transducers. Female participants ran at 8 and 9 km h(-1) and male runners ran at 9 and 10 km h(-1). Participants were novice female and male recreational runners and were followed during a 9-week running program. RESULTS Two hundred and ten novice runners enrolled this study, 133 (63.3%) female and 77 (36.7%) male runners. Thirty-four runners reported an RRI. At baseline SA values varied widely for all spatio-temporal and kinetic variables. The inter-individual differences in SA were also high. No significant differences in SA were found between female and male runners running at 9 km h(-1). In injured runners the SA of the impact peak was significantly lower compared to noninjured runners. CONCLUSIONS Natural levels of asymmetry in running were high. The SA of impact peak in injured runners was lower compared to noninjured runners and no differences were seen between the injured and noninjured lower limbs.

The NLstart2run study: health effects of a running promotion program in novice runners, design of a prospective cohort study

BackgroundRunning is associated with desirable lifestyle changes. Therefore several initiatives have been undertaken to promote running. Exact data on the health effects as a result of participating in a short-term running promotion program, however, is scarce. One important reason for dropout from a running program is a running-related injury (RRI). The incidence of RRIs is high, especially in novice runners. Several studies examined potential risk factors for RRIs, however, due to the often underpowered studies it is not possible to reveal the complex mechanism leading to an RRI yet.The primary objectives are to determine short- and long-term health effects of a nationwide “Start to Run” program and to identify determinants for RRIs in novice runners. Secondary objectives include examining reasons and determinants for dropout, medical consumption and economical consequences of RRIs as a result of a running promotion program.Methods/designThe NLstart2run study is a multi-center prospective cohort study with a follow-up at 6, 12, 24 and 52 weeks. All participants that sign up for the Start to Run program in 2013, which is offered by the Dutch Athletics Federation, will be asked to participate in the study.During the running program a digital running log will be completed by the participants every week to administer exposure and running related pain. After the running program the log will be completed every second week. An RRI is defined as any musculoskeletal ailment of the lower extremity or back that the participant attributed to running and hampers running ability for at least one week.DiscussionThe NLstart2run study will provide insight into the short- and long-term health effects as a result of a short-term running promotion program. Reasons and determinants for dropout from a running promotion program will be examined as well. The study will result in several leads for future RRI prevention and as a result minimize dropout due to injury. This information may increase the effectiveness of future running promotion programs and will thereby contribute positively to public health.Trial registrationThe Netherlands National Trial Register NTR3676. The NTR is part of the WHO Primary Registries.

Rocker shoe, minimalist shoe, and standard running shoe: A comparison of running economy

OBJECTIVES Running with rocker shoes is believed to prevent lower limb injuries. However, it is not clear how running in these shoes affects the energy expenditure. The purpose of this study was, therefore, to assess the effects of rocker shoes on running economy in comparison with standard and minimalist running shoes. DESIGN Cross-over design. METHODS Eighteen endurance female runners (age=23.6 ± 3 years), who were inexperienced in running with rocker shoes and with minimalist/barefoot running, participated in this study. Oxygen consumption, carbon dioxide production, heart rate and rate of perceived exertion were measured while participants completed a 6-min sub-maximal treadmill running test for each footwear condition. The data of the last 2 min of each shoe condition were averaged for analysis. A linear mixed model was used to compare differences among three footwear conditions. RESULTS Oxygen consumption during running with rocker shoes was on average 4.5% higher than with the standard shoes (p<0.001) and 5.6% higher than with the minimalist shoe (p<0.001). No significant differences were found in heart rate and rate of perceived exertion across three shoe conditions. CONCLUSIONS Female runners, who are not experienced in running with the rocker shoes and minimalist shoes, show more energy expenditure during running with the rocker shoes compared with the standard and minimalist shoes. As the studied shoes were of different masses, part of the effect of increased energy expenditure with the rocker shoe is likely to be due to its larger mass as compared with standard running shoes and minimalist shoes.

The NLstart2run study: Incidence and risk factors of running-related injuries in novice runners

Running is a popular form of physical activity, despite of the high incidence of running‐related injuries (RRIs). Because of methodological issues, the etiology of RRIs remains unclear. Therefore, the purposes of the study were to assess the incidence of RRIs and to identify risk factors for RRIs in a large group of novice runners. In total, 1696 runners of a 6‐week supervised “Start to Run” program were included in the NLstart2run study. All participants were aged between 18 and 65, completed a baseline questionnaire that covered potential risk factors, and completed at least one running diary. RRIs were registered during the program with a weekly running log. An RRI was defined as a musculo‐skeletal complaint of the lower extremity or back attributed to running and hampering running ability for three consecutive training sessions. During the running program, 10.9% of the runners sustained an RRI. The multivariable Cox regression analysis showed that a higher age, higher BMI, previous musculo‐skeletal complaints not attributed to sports and no previous running experience were related to RRI. These findings indicate that many novice runners participating in a short‐term running program suffer from RRIs. Therefore, the identified risk factors should be considered for screening and prevention purposes.

The NLstart2run study : Training-related factors associated with running-related injuries in novice runners

OBJECTIVES The incidence of running-related injuries is high. Some risk factors for injury were identified in novice runners, however, not much is known about the effect of training factors on injury risk. Therefore, the purpose of this study was to examine the associations between training factors and running-related injuries in novice runners, taking the time varying nature of these training-related factors into account. DESIGN Prospective cohort study. METHODS 1696 participants completed weekly diaries on running exposure and injuries during a 6-week running program for novice runners. Total running volume (min), frequency and mean intensity (Rate of Perceived Exertion) were calculated for the seven days prior to each training session. The association of these time-varying variables with injury was determined in an extended Cox regression analysis. RESULTS The results of the multivariable analysis showed that running with a higher intensity in the previous week was associated with a higher injury risk. Running frequency was not significantly associated with injury, however a trend towards running three times per week being more hazardous than two times could be observed. Finally, lower running volume was associated with a higher risk of sustaining an injury. CONCLUSIONS These results suggest that running more than 60min at a lower intensity is least injurious. This finding is contrary to our expectations and is presumably the result of other factors. Therefore, the findings should not be used plainly as a guideline for novices. More research is needed to establish the person-specific training patterns that are associated with injury.

Effect of rocker shoes on plantar pressure pattern in healthy female runners

Rocker profile shoes (rocker shoes) are one of the treatment options of metatarsalgia and forefoot stress fractures. The efficacy of rocker shoes in unloading the forefoot pressure has been shown in walking. In running, however, the effect of rocker shoes on forefoot pressure is unknown. Eighteen healthy female runners participated in this study. In-shoe plantar pressures were recorded during running with the standard running shoes and rocker shoes. Shoe comfort was assessed after each shoe measurement. Peak pressure (PP), maximum mean pressure (MMP) and force-time integral (FTI) were determined for seven foot areas. The effects of shoes on the different outcome variables were statistically analyzed using a linear mixed model. Running with the rocker shoes caused a significant reduction (p<0.001) in all pressure parameters in the central and lateral forefoot. FTI and MMP were also reduced by 11% and 12% in the medial forefoot while running with rocker shoes. Running with rocker shoes resulted in a significant increase in all pressure parameters at the heel region (p<0.001). Running with rocker shoes received a significant (p<0.01) lower comfort rate than running with standard running shoes. Rocker shoes might be beneficial for runners who are recovering from metatarsalgia or stress fractures of the forefoot region, as it reduces plantar pressure in the forefoot region.

Biomechanics of running with rocker shoes.

OBJECTIVES Load reduction is an important consideration in conservative management of tendon overuse injuries such as Achilles tendinopathy. Previous research has shown that the use of rocker shoes can reduce the positive ankle power and plantar flexion moment which might help in unloading the Achilles tendon. Despite this promising implication of rocker shoes, the effects on hip and knee biomechanics remain unclear. Moreover, the effect of wearing rocker shoes on different running strike types is unexplored. The aim of this study was to investigate biomechanics of the ankle, knee and hip joints and the role of strike type on these outcomes. DESIGN Randomized cross-over study. METHODS In this study, 16 female endurance runners underwent three-dimensional gait analysis wearing rocker shoes and standard shoes. We examined work, moments, and angles of the ankle, knee and hip during the stance phase of running. RESULTS In comparison with standard shoes, running with rocker shoes significantly (p<0.001) reduced the positive (16%), and negative (32%) work at the ankle joint. Plantar flexion moment peak and impulse were also reduced by 11% and 12%, respectively. Reduction in these variables was almost two times larger for midfoot strikers than for rearfoot strikers. At the knee joint running with rocker shoes significantly increased the positive work (14%), extension moment peak (6%), and extension moment impulse (12%). CONCLUSIONS These findings indicate that although running with rocker shoes might lower mechanical load on the Achilles tendon, it could increase the risk of overuse injuries of the knee joint.