Research review- Running technique is an important component of running economy and performance (Folland, Allen, Black, Handsaker & Forrester, 2017)
Running technique has been related (Barnes, Kilding, 2015, p.37-56) to both performance and factors in an overall running economy. The reviewed study (Folland, Allen, Black, Handsaker & Forrester, 2017) aimed to establish a relationship between kinematic variables and performance we well as running economy (RE), described here as locomotive energy (LE). The study set five general categories of kinematics to be examined, with an overall number of 24 parameters included:
1. Stride parameters (shorter ground contact time or cadence). Swing time and duty factors were not studied under the current research but are noted as of importance.
2. Lower limb angle: foot strike, or foot angle at landing. Goes up the kinetic chain to shank and thigh. Stiffness is another important factor as well as the free moment of the swinging leg (could be angle of hip extension). Minimum knee angle during stance & swing.
3. Vertical oscillation- mainly amplitude in center of mass and pelvic oscillation.
4. Horizontal velocity during ground contact (braking): expensive reacceleration required unless minimizing the horizontal velocity.
5. Trunk & pelvis orientation (posture): forward lean and transverse pelvis.
Out of those 5 categories, 24 kinematic variables were selected based on literature and likelihood to correlate to RE and performance.
Energy cost was defined and measured through metabolic testing using blood sampling to determine VLTP , and detection of an exchange of respiratory gases and ventilation rate.
Field of participants included 97 runners, 47 females and 50 males. In light of the wide range of abilities needed for this study, 86 recreational runners and 11 sub-elite (set criteria of faster than 31 minutes 10K race time for men and faster than 35 minutes for women, respectively) were recruited. Participants’ best time score from a race ran in the past 12 months was used as an individual baseline for each of the runners.
Physical variances between the participants used main anthropometric measures, including height, weight, body mass index and thickness of fat tissue.
The study was designed in a climate-controlled lab, where participants ran at the same time of the day (morning), on a treadmill, in two visits set about 14 days apart. Prior testing was not performed to detect any substances in the blood.
Metabolic standards included respiratory rating using exchanges of gas, where the participants exhaled into a specialty mask equipped with a turbine and pre-calibrated using a set (known) concentration of CO2, O2 and ambient air. Both volume and concentration of gases were recorded. The study describes these as “Energy costs” and a baseline was achieved while participants stood still for 2 minutes on a treadmill prior to running. All runners were instructed to stand at the same anatomical stance with elbows flexed and feet at shoulders’ distance. Motion capturing system
The running protocol included several segments of running at a set speed; starting from 7 KPH for the women, 8 KPH for the men and increasing the speed by 1 KPH every 4 minutes. 30 seconds of rest “divided” those increments and a blood sample from the fingertip was taken to measure lactic acid in the blood. The incremented run trial terminated when the lactic acid level rose by 2 mmolILj1 or exceeded a total of 4 mmolILj1. Then, a continuous run trial was executed: runners increased their speed by 1KPH till reaching an exhaustion stage of ventilation.
To assume, or set, a baseline of gas exchange, a breath-to-breath testing was done; omitting random breathing caused by coughing etc. the following physiological modules were quantified:
· VO2 (Oxygen consumption) - taken at the last 60 seconds of the submaximal effort / 30 seconds of still standing. Peak consumption was determined from a 30 seconds average of highest moving times.
· VCO2 (Carbon Dioxide production)
· VE (ventilation rate)
VLTP is the point above which the lactate acid accumulates faster in the blood and implies a greater intensity of exercising (Midgley, Mc Naughton & Wilkinson, 2006). Lactate threshold was identified to help determine VLTP. This threshold was later used to terminate the incremented run and transition the runners into the continuous run session.
A maximal level of lactic acid (>2 mmolILj1 or exceeding 4 mmolILj1 ) determined the timed termination of the incremented run, transitioning the runners into a continuous session.
Running economy, specifically energy expenditure, was measured both during the last minute of the incremented run as well as the still standing using VO2 and VCO2. Researchers were able to exclude anaerobic metabolic factors into the RE through absolute measure of fat and carbohydrates consumption. This is important when analyzing running performance, which is almost completely aerobic in nature. Locomotive energy cost was measured as part of the overall running economy and still standing LEc was excluded, to enable the measurement of LEc, expressed in calories per Kg per Km.
The kinematic variables were detected through a 3D visual, marked on 17 different body areas were joint centers and body angles were identified individually per participant. Each velocity, counted at the 15th second into the run, analyzed 10 consecutive strides. Into the stride, analysis of steps (each leg separately, or “half a stride”), instances of touchdowns and toe-off phases were detected within a certain, pre-defined window of time in which they occurred (in each step). Other main kinematics analyzed the vertical oscillation; horizontal (braking) velocity and trunk posture (or, mean forward lean and transverse pelvic movements).
Stride analysis was also used to analyze spatiotemporal parameters in relation to ground contact time, including 8 measurements of hip and knee angles which have been suggested to affect running economy and performance (Pohl & Buckley, 2008).
Taken into account were sex-dependent variables which were found: Locomotive energy, lactate turning point and seasonal best. Statistical variance was demonstrated greatly in parameters such vertical oscillation and braking forces.
According to the relation of the kinematic parameters to factors measured (locomotive energy, lactate turning point and seasonal best), a strong relationship has not been observed. Nevertheless, vertical oscillation has been linked to performance (where larger oscillation related to worse performance). This is perhaps due to resulting increased energy requirements. Braking was associated to performance were lower horizontal force (decelerated) related to worse performance. Additional parameters of braking initially included in the study were not proved to be related to performance or economy in general. Unsurprisingly, greater transverse movements of the pelvic required greater energy costs and were related to worse performance. Shorter ground contact time shoed relation to better economy but not found to improve performance. Greater angles of the lower limbs, both at touchdown and swings phases, were related to worse performance.
4 variables were studied: Running kinematics, economy, VLTP and performance. Out of the kinematic parameters studied in relation to those, four were related strongly to performance: horizontal velocity of pelvis, shank angle during touchdown, duty factor and forward lean. This is rather innovative evidence since pervious literature was not able to portray such relationship. Since running economy was largely defined as locomotive energy, a wide range in energy costs was noted in the cohort, in part due to the extraction of resting energy cost done to isolate the running energy requirements. The study was able to set a connection between the physiological marker of performance, defined as the lactate turning point, and 4 consistent kinematic parameters. The laboratory setting might explain some of the consistency, as opposed to field racing in which climate, terrain and other condition might differ and affect the results. Conflicting evidence was noted between the reviewed study and previous literature (Williams, Cavanagh, 1987) in the relationship between breaking forces and running economy, in particular within elite female runners. This might require a further pre-classification or pre and post-natal stratification. The logic of this relationship is described in the study. Greater forces at braking during ground contact demand the recreation of greater horizontal propulsion forces after ground contact, in order maintain the same velocity- a costly requirement in terms of metabolic energy.
Vertical oscillation of the pelvic correlated with the variables repeatedly throughout the study and mentioned again the claim that leg stiffness and less vertical displacement could be beneficial to running economy. This might be due to the more energy required to work against gravity, when the pelvic is more vertically oscillated.
A thought-provoking relation was noted in the forward lean of the trunk: decreased range of motion was somewhat related to performance, however not to economy. This stands in conflict to a previous, comprehensive study (Williams, Cavanagh, 1987).
Duty factor which is consequent to ground contact time was related to performance but not to economy; this leads to questioning the popular assumption relating running economy to performance. This, by itself, is a valuable point brought up by this study .
Schubert, Kempf and Heiderscheir (2014) found a possible explanation to the contribution of shorter ground contact time to performance, noting that leg stiffness increases stride rate which in turns reduces the energy absorbs in the joint thus reducing vertical oscillation (however, not in the pelvic but in the center of mas which has not been related to either running economy, or performance, in this study). Lower limb angles were found to be negatively related to performance when angles were larger. The study mentions the possibility of greater anterior extension of the leg (“over striding”) as a possible cause. There is a practical importance in this finding, since coaching cues include a “heel pick up” instruction and might in fact be unnecessary since greater flexion of the swinging leg has been related to running economy, however not to actual performance.
He study found that individual technique (namely, shank angle) was kept consistent throughout changes in speed mainly with elite runners. Running technique was found to be related to lactate turning point and is influenced by speed, therefore assuming another base to the connection between kinematics and performance. Locomotive energy was found to have a greater impact on performance in comparison to mere kinematics. The study outlines anatomical recommendations to improve performance, such as improved stride parameters, minimized vertical oscillation and transverse pelvic movements.
References in the critiqued article
The study relies on a vast amount of previous literature. After reading some of the key studies referenced, I have a strong base of faith in the effort of the authors to research previous evidence. APA formatting is consistent, both in-text and as references.
The keywords are provided following the abstract and include kinematics, energy costs, running and more frequent topics. No running head was provided but footer with a summarized version of the article name is present. The article mentioned the informed consent and the supervision, as well as funding, to the study. The laboratory setting seemed to have influenced the results and calls for a field study. The predictor was defined as kinematics and the outcome as running economy and performance.
Folland, J. P., Allen, S. J., Black, M. I., Handsaker, J. C., & Forrester, S. E. (2017). Running technique is an important component of running economy and performance. Medicine and science in sports and exercise, 49(7), 1412.
Barnes KR, Kilding AE. Strategies to improve running economy. Sports Med. 2015;45(1):37–56.
Midgley, A. W., Mc Naughton, L. R., & Wilkinson, M. (2006). The Relationship between the Lactate Turnpoint and the Time at V· O2max during a Constant Velocity Run to Exhaustion. International journal of sports medicine, 27(04), 278-282.
Pohl, M. B., & Buckley, J. G. (2008). Changes in foot and shank coupling due to alterations in foot strike pattern during running. Clinical Biomechanics, 23(3), 334-341
Williams KR, Cavanagh PR. Relationship between distance runningmechanics, running economy, and performance. J Appl Physiol. 1987;63(3):1236–45.)
Schubert AG, Kempf J, Heiderscheit BC. Influence of stride frequency and length on running mechanics: a systematic review. Sports Health. 2014;6:210–7