Considerations for Healthy Running Habits: A Deeper Dive into the ACSM Infographic
Heather K. Vincent, Ph.D., FACSM; Kevin R. Vincent, Ph.D., M.D., FACSM
Running continues to be a popular physical activity for individuals across the age spectrum. People who run are varied in their physical fitness capacity, body habitus, training histories and medical conditions. Using a combination of scientific evidence and valuable clinical experience from scientists and practitioners that has been emerging over the last 15 years, we developed an infographic to offer cues that can be adopted to help endurance runners reduce features of running motion that are related to preventable injury. The intent of this infographic was to carefully synthesize outcome patterns from the available mixed-method evidence and ongoing work, and translate the information into practical use — irrespective of the different characteristics of the distance runner. Given that no “gold standard” exists to retrain all runners, we provide in this infographic some habits to help keep people running safely.
The main goals of the habits provided were to (a) reduce potential risks related to injury, including impact loading rates, foot reach out in front of the center of gravity and stride width; and (b) to improve co-activation of muscles that can buffer impact loading and reduce stresses related to chronic musculoskeletal pain (e.g., IT band syndrome, patellofemoral pain, Achilles pain, hip pain) or bony injuries (e.g., lower-extremity and foot stress fractures; see references for sample mechanical features related to injury risk in runners). From others’ research and our ongoing work, retraining sessions involve cueing and different methods to support learning uptake, such as metronome use, real-time visual feedback, meeting projected motion targets on a screen to retrain runners to a cadence that fosters less injury risk to the musculoskeletal system (data to be uploaded in abstract form and paper in 2022-23). We provide before-and-after comprehensive kinematic-kinetic output from our own and other programs to determine whether appropriate mechanical changes are occurring that correspond to the specific issues identified by the physician or physical therapist. Several of the running habits described can work together in overlapping ways for additional improvement in injury risk. Adoption of a few different modifications together may feel more natural and easy to do than individual cues and be effective on injury risks (Huang et al. 2019).
As the science continues expanding and innovations in clinical practice rapidly occur, we expect these habits/cues to be improved over time and coupled with other interventions as other researchers have — such as footwear (Futrell et al. 2020; Wang et al. 2020) and strengthening programs (Miller et al. 2020). The consideration of both scientific study and clinical expertise from practitioners who work directly with patients (Barton 2016) is critical for advancing injury prevention and treatment efforts for this population as the field evolves. Charleton et al (2021) acknowledge that cueing can be a combination of implementing external foci (such as “running quietly and softly”) and internal foci (such as “keeping kneecaps facing forward”), and skill acquisition and learning processes can take time for runners to adopt. The infographic is meant to serve as a platform from which retraining efforts may start, and it is acknowledged that additional study is needed to determine the persistence of cue application for durations longer than one month to one year as has been published (Bowser et al. 2018; Bramah et al. 2019; Chan et al. 2018; Diebal et al. 2012; Futrell et al. 2020; Fyock et al. 2019).
Of note, published gait-retraining efforts often include biofeedback of some form (e.g., visual, mirror, auditory, wearable sensors) supported by cueing (Willy et al 2012; Noehren et al. 2011; Roper et al. 2016). Gait retraining from one to more than eight sessions have used a variety of techniques to change mechanical stressors and kinematics associated with bony and soft tissue injuries. Using visual feedback and these cues can help runners understand the impact of the cue, especially early in the learning of the skill. However, if runners don’t have instrumentation to use or biofeedback mechanisms, what are some healthy habits runners can adopt to help mitigate injury risk?
Increasing cadence (step rate). Increasing cadence anywhere from 5 to 30% depending on the research appears to confer several protective mechanical benefits against injury. For many of these studies, when adjustments are made from habitual cadence by 5-10% , the “faster” cadence is generally increased >170 steps per minute (Adams et al. 2018; Futrell et al 2020; Hiederscheit et al. 2011; Vincent et al. 2019). Some intervention studies used a specific target for cadence for all runners in the study (for example, a change from a habitual cadence to a set target of 180 steps/min; Miller et al. 2021). Schubert et al. (2014) provided a systematic review of the effects of faster cadence (and shorter stride length) on running injury risks. Protective benefits against musculoskeletal injury can include reduction of vertical ground reaction forces and impact shock, vertical average loading rate (VALR) adduction hip angle, shorter reach of the leading foot through shorter step length; co-activation of hip and hamstring muscles can also increase (Chumanov et al. 2012; Futrell et al. 2020; Heiderscheit et al. 2011; Hobara et al. 2012; Miller et al. 2021). In addition, a higher cadence reduces vertical oscillation, or “bounce,” of the center of mass and reduces braking impulses and stride width (Adams et al. 2018; Vincent et al. 2019) at level or downhill grades and reduces the loading impulse at the heel (Wellenkotter et al. 2014). Tibial rotation, sagittal and rearfoot angles are all reduced with a faster cadence (Farina and Hahn 2021).
In many lab studies, cadence can be successfully increased using auditory metronome feedback (Busa et al. 2016; Heiderscheit et al. 2011; Vincent et al. 2019) In field studies using insole shoe sensors and metronomes, runners were able to increase cadence by ~7.8% from habitual (from 166 to 178 steps/min), which corresponded to significant reductions in peak vertical ground reaction force (GRF) over a two-mile run (Musjgerd et al. 2021). Translation studies that retrained runners with a 12-week graduated cadence-retraining program in their own training environment (monitored through apps) increased habitual cadence by 5.7% (from 161 to 171 steps/min) and reduced step length, vertical excursion of center of mass, vertical velocity of center of mass and foot angle at initial ground contact (Wang et al. 2020). Importantly, for runners who use wristwatch devices to track running parameters, this cue appears to be achievable by self when out on the field (Adams et al. 2018). For runners with higher body weights, experimental data show that a modest increase in cadence may be applied to help offset patellofemoral/tibiofemoral joint contact forces (Willy et al. 2016). Self-administration of cadence targets with metronomes on GPS smartwatches in the natural home environment followed by gradual withdrawal of the metronome stimulus successfully increased cadence from 166 to 185 steps per minute, was maintained at 181 steps per minute by month three.
Cueing cadence can also help widen stride/step, position foot landing closer to the center of gravity and reduce excessive bounce. Collectively, the leading leg lands with a horizontal distance closer to the hip at initial contact, especially with a forefoot strike. In our recent work of retrained runners, the cue of increasing cadence to greater than 170 steps per minute (can be as high as 185 steps/min) is associated with an average step width increase of 1.3 cm (17% increase).
Short, quick steps. During running, considerable mechanical energy must be absorbed during the impact of each step, and lower extremity muscles contract eccentrically to slow the descent of the body mass (Winter 1983). Energy absorption occurs largely at the knee joint, and if the muscles do not adequately absorb energy with changes in speed or slope, passive tissue structures along the kinetic chain may be at risk for overloading (Derrick et al. 1998). Long strides correspond to high tibial acceleration peaks and relatively less shock attenuation and higher vertical GRF than shorter strides (Busa et al. 1016; Stergiou et al. 2003). Earlier work showed that the coordinated angular velocities of subtalar and knee were disrupted with long versus shorter stride lengths (Stergiou et al. 2003), which could have implications for onset of chronic injuries. Seay et al. (2008) found that in vivo, lumbaosacral forces (transverse T12-L1 and sagittal L5-S1 moments) increased with stride lengthening. Shortening step lengths can immediately minimize these mechanical issues. A shorter step will also facilitate less anterior foot placement in front of the body relative to the center of gravity, which improves stability and prevents slipping (van Oeveren et al 2021).
The cue of “Take short, quick steps” goes hand in hand with increasing cadence, and some runners may respond better to these words than “Increase your cadence” — the goal, of course, is the same. This cue has been used in retraining studies of military personnel with history of running injury (Miller et al. 2021) In either case, a shortening of step length by 10% from habitual length can significantly reduce patellofemoral joint reaction forces, peak tibiofemoral contact force, force impulse per step and average loading rate at the tibiofemoral joint and medical compartment compared to longer steps, irrespective of foot strike type (Bowersock et al. 2017a; Willson et al. 2015). Importantly, this cue has been found to reduce these same knee forces among runners with a history of ACL reconstruction, giving support to this as a possible clinical intervention for this part of the population (Bowersock et al. 2017b). From the kinematic perspective, pelvic drop, hip adduction and rearfoot eversion decreases as stride length increases (Boyer and Derrick 2015).
Short steps can also facilitate wider steps. This is of interest, because narrow step width is related to shear stress on the tibia (Meardon and Derrick 2014). Compression on the posterior and medial aspects of the tibia are inversely related to step width; so, as step width increases, compression on the surface of tibia can be reduced (Meardon and Derrick 2014), which has implications for runners with patellofemoral pain and patellofemoral arthritis; shorter steps can help offset foot crossover risk and associated tibial stresses through footstep widening. We provide a brief technique pearl for runners in adopting less foot crossover to support the short quick steps (Kilgore 3rd et al. 2020). Some cues that may help this process include “Imagine the pedaling motion of cycling and keep your feet wide enough to pedal the bike,” “Imagine running with your left foot on the left side of a road line and your right foot on the right side of the line” and “Imagine jump roping and moving forward.” With deliberate directed increases in step width compared to a foot crossover pattern, several mechanical changes occur, including reduction of hip adduction, rearfoot eversion angle, knee abduction moment and impulse and rearfoot inversion moment (Brindle et al. 2014).
Squeeze gluteal muscles and point kneecaps forward. Impaired ability to control frontal and transverse pelvic and hip motion manifests as hip internal rotation, contralateral pelvic drop and hip adduction. These features are related to various injuries in runners such as patellofemoral pain (Willson and Davis 2008), sacroiliac pain (Whitney et al. 2022) and medial tibial stress syndrome (Becker et al. 2018; Menendez et al. 2020). Also, gluteus medius activation is lower and delayed in runners with patellofemoral pain versus healthy runners (Willson et al. 2011); data from healthy, non-injured runners show significant activation of deep gluteal muscles during loading and that these muscles are a good target for rehabilitation (Nunes et al. 2020). Systematic reviews acknowledge that the state of the evidence, while limited in volume, shows alignment in the ability to target these hip mechanics for better running mechanics and favorable clinical outcomes (Neal et al. 2016).
To activate relevant muscles and address motion impairments, runners with patellofemoral pain have been instructed to contract/ squeeze the gluteal muscles together while attempting to keep the knees pointing directly ahead and pelvis level as part of a retraining program. These directives were supported by visual feedback of anatomically placed reflective markers on a screen (Noehren et al. 2011); improvements in hip adduction and contralateral pelvic drop occurred commensurate with pain relief (Noehren et al. 2011). Another intervention study used mirror retraining and tester verbal cues of “Run with your knees apart with your kneecaps pointing straight ahead” and “Squeeze your buttocks” until the adjustments were made during sessions (Willy et al. 2012); after the training period, runners reduced hip adduction and contralateral pelvic drop and reported reductions in knee pain severity. An important point to note is that there may be variable responsiveness to specific types of cues and feedback — other investigators and our lab has found that some runners adopt new motion habits more quickly than others (Chan et al. 2020; Willy and Davis 2013). The goal moving forward is to develop different visualization methods or cues that can be explored to help runners understand how to acquire the healthy running habit.
We fully acknowledge that anatomic variations exist in natural tibial alignment relative to the femur. The intent of this habit is to encourage the runner as much as possible to envision keeping the knees anteriorly directed, which can also facilitate widening stride width.
Landing softly and quietly. Gait-retraining studies have directly used this specific cue to modify how runners interact with the ground (Bowser et al. 2018; Cromwell & Davis 2011; Diebal et al. 2012; Phan et al. 2017). To achieve soft quiet foot landings, each runner may use a slightly different motor strategy, — Runners may use a more forefoot strike, better leg and hip muscle activation patterns during swing to prepare for stance phase in the gait cycle, adjustment of lower limb joint or trunk joint angle positions, less sound on ground impact or a combination of any of the these. Adopting a more mid-to-forefoot landing pattern and getting away from a hard heel strike can produce mechanical changes: (a) the landing strike position can change the muscle activation patterns at the gluteals and hamstrings, (b) improve joint angle positions and reduce excessive motion during the gait cycle and (c) reduce the impact stresses on the body.
A transition from a rearfoot a forefoot strike may offer a strategy for some runners to use when learning to land softly. Once learned, the motor pattern can be retained and the associated protective reductions in VALR can persist for at least six months (Futrell et al. 2020). First, instructing/cueing habitual rearfoot runners to adopt patterns closer to forefoot striking increased peak gluteal activation, and this corresponds to reduction in peak hip adduction, hip internal rotation and heel-center of gravity distance. Foot reach position is reduced may lead to reductions in peak knee extensor moments (and associated quadricep force), patellofemoral joint forces and stress (Lenhart et al. 2014a; Lenhart et al. 2014b; Vannatta 2017). Second, landing with a non-rearfoot strike pattern changes several mechanical features (summarized in Almeida et al. 2015). Forefoot landing results in a more plantar-flexed ankle and flexed knee position compared to runners with rearfoot strike (Miller et al. 2021). Knee flexion angle at initial contact increases and total knee excursion decreases (Cromwell & Davis 2011). Adopting a more forefoot strike can also reduce sagittal plane lumbar spine motion (Delgado et al. 2013), which has implications for modifying back pain in runners. Third, compared to rearfoot strike, landing off the heel can help reduce the impact transient early in the stance phase of loading (Lieberman 2010), and reduce the impact peak and peak positive acceleration (Cromwell & Davis 2011), GRF and average/peak vertical loading rates (Phan et al. 2017; Yong et al. 2018). In addition, peak quadriceps force and average hamstring force decreased, whereas gastrocnemius and soleus muscle forces increased when running with a forefoot strike. It is important to point out that a recent systematic review found low evidence of a relationship between foot strike type and onset of running injury (Burke et al. 2021) which could indicate that landing softly and quietly — irrespective of foot strike type — may be a better focus for runners as they modify their form.
In runners with patellofemoral pain, forefoot gait retraining induces clinical improvement in knee pain symptoms using cues such as “run on your toes” or “run on the balls of your feet,” commensurate with reduction in ankle dorsiflexion angle and knee abduction angle at initial contact and increased ankle loading (Roper et al. 2016). Six-week long forefoot-run retraining programs can reduce pain symptoms, improve running tolerance and significantly decrease intra-compartmental pressures among individuals with chronic exertional compartment syndrome (Diebal et al. 2012); running distance performance also increased 300% after the intervention. Even among healthy runners with high tibial shock values, soft landing and visual feedback can help reduce risk for impact-related injuries (Bowser et al. 2018).
Tuck in the chin and control forward lean. Data from small studies in healthy runners show varying effects of anterior trunk lean. For example, anterior lean shows mixed benefit on controlling patellofemoral joint forces (Dos Santos et al. 2019; Teng and Powers 2014) but no effect on GRF (Shih et al. 2019) or impact loading (Huang et al. 2019; Xia et al. 2021). During stance, an isolated modification of trunk lean increases knee flexion angle and hip extensor moment compared to habitual heel striking pattern (Dos Santos et al. 2019). Trunk lean may also be related in part to the incidence of running-related soft-tissue injuries (Bramah et al. 2018). A synopsis of the literature suggests that trunk lean also contributes to a more anterior placed foot at foot strike, but whether using an exaggerated trunk lean should be generally advised is not clear (Shih et al. 2019; van Oerveren et al. 2021). Moderate-to-high trunk flexion postures increase the distance of foot reach in front of the center of gravity, impact transients and rate of loading while increasing the hip moment (Warrener et al. 2021).
Using a “natural” lean that is not excessive and can be accomplished while engaging in other healthy motion habits may feel easier to do (Huang et al. 2019). Gait retraining studies have used cues to help runners achieve a slight forward bend of the trunk and foster healthier posture and mechanical patterns (dos Santos et al. 2019; Miller 2021). However, excessive forward lean from poor posture or fatigue (Koblbauer et al. 2013) may strain the lower back muscles and contribute to subsequent injury to the low back structures and hamstrings (Apte et al. 2021). At this time, a reasonable habit to adopt while running is a slight forward lean that is not initiated at the waist and not lead by the head and neck.
The cues published by others to “run with an increase in flexed trunk,” “lean forward from your ankles” and “lean your trunk forward” were not consistently interpreted the same way within our diverse general runner population of all ages from 7 to 85 years. These cues may be perfect for homogeneous younger runners, but in our experience, some runners overcompensate and excessively lean forward through a bend at the waist. While we completely agree with other investigators that some forward lean is important and necessary, we offer that through clinical experience other cues such as “tuck in the chin” or “pretend you are pulling up a string through the spine and head” can also help improve trunk posture and prevent leading with the neck stretched anteriorly. The overall goal is the same. We offer that a variety of cues may be tried until the effect is achieved of the non-leading head position with slight forward whole-body lean is a good position to promote more healthy loading during stance phase of gait compared to bent at the waist or arched back with excessive lordosis.
Abdominal tone. Through observation studies, we can learn from runners who are naturally adopting techniques to reduce musculoskeletal discomfort. For example, runners with patellofemoral pain adopt a more rigid stabilization strategy at the pelvis, which has been interpreted as a potential adaptation to prevent further pelvic drop and frontal plane malalignment at the knee (Haghighat et al. 2021). Clinical rehabilitation treatments can leverage this strategy to help control distal kinematics contributing to musculoskeletal pain. For example, abdominal drawing-in techniques can reduce knee adduction moment compared to not using this technique while walking (Fujita et al. 2021). Case reports have shown that runners with hip and low back pain (postpartum) may benefit from dynamic lumbar stabilization that combined running form modification and abdomen drawing-in maneuvers. Transverse abdominis muscle thickness increased over time, and this change corresponded to better lumbopelvic control (pelvic drop and pelvis axial rotation) and resolution of pain symptoms (Thein-Nissenbaum et al. 2012). Abdominal engagement can be applied acutely to running for injury prevention as well. A method to help runners achieve this abdominal bracing is provided in a clinical pearl (Vincent and Vincent 2018). Bracing techniques facilitate and increase activation of internal oblique and external oblique muscles (Fujita et al. 2021).
Linear arm swing. During running, the lower body and upper body rotate in opposite directions about the longitudinal axis, with opposite vertical angular momenta (Hamner & Delp 2013; Hinrichs 1987). To keep a person running forward in a straight line, the vertical angular momentum produced by the lower body needs to be counteracted by the upper body (van Oeveren et al. 2021). One way to achieve this is to keep the arms swinging linearly at the sides of the body. In cases where the runner is not adequately producing angular momentum with the upper body, the arms and hands will swing in front of the torso. For some running styles that focus on anterior placement of the foot and emphasis on push-off as occurs with higher speeds, the arm swing becomes a particularly important compensation (Hinrichs 1987).
The trunk and pelvis contribute relatively little to the whole-body rotation about the vertical axis as the masses are situated close to the axis (Brujin et al 2008; Hinrichs 1987). As such, arm swing may be important for producing the compensatory angular momentum and injury prevention perspectives. During stance, there is a large exorotation moment produced about the hip on the stance side. This free moment is transferred over the knee and is related to tibial stress and knee injuries (Milner et al. 2006; Pohl et al. 2008; Willwacher et al. 2016) and may increase the workload on the hip muscles. Besides using upper body motion to control whole body rotation during the gait cycle, the runner can offset whole body rotation by producing an exorotation about the hip on the side of the stance leg (van Oeveren et al. 2021) — potentially through gluteal activation. Lowering the overall angular momentum around the vertical axis by producing compensatory upper body angular moments through arm swing may be useful in reducing injury risk (van Oeveren et al. 2021).
Break up the run and take breaks. Take breaks and/or try intervals to break up a run if fatigued. Reminding runners not to keep running through is prudent to help minimize exposure to deteriorating mechanics. This is particularly true for novice runners compared to competitive runners — acute fatigue has a more profound effect on biomechanical parameters such as forward trunk lean and hip adduction, which in turn may heighten stresses on musculoskeletal tissues (Maas et al. 2018). Recent work and systematic reviews found that fatigue-induced alterations in biomechanics are widespread — from increased contact time to decreased maximal knee flexion angles at initial contact and swing. (Apte et al. 2021, Yu et al. 2021). Fatigue also changes features of motion related to increased risk of injury, including reduced cadence, increased upper body rotation, increased lower leg position at heel strike, decreased knee flexion during stance and decreased leg stiffness (Apte et al. 2021; Mohler et al. 2021; Winter et al. 2017). Guiding runners to listen to their bodies and feel when motion is changing, or footfalls are becoming louder, steps are lengthening and arm swing crosses the body — take a walk break and avoid falling into unfavorable mechanics.
Putting it together. Using the healthy habits presented in this ACSM infographic, we have worked to help recreational distance runners in our clinic and laboratory achieve a healthy pattern of motion. The paper is in preparation and in abstract form for ACSM 2023. At this time until 2-6 months post retraining, runners have not reporting recurrence of the injury that brought them to the clinic or recurrence of pain. We follow these runners as they participate in their physical therapy and over the long term. The following data were obtained, with all reported changes as statistically significant:
Cadence shift from 163 ± 9 steps/min to 175 ± 9 steps/min and reduction in gait cycle time from 0.73 ± 0.04 s to 0.68 ± 0.03 s. Center of gravity vertical displacement naturally lowered (from 9.8 ± 1.2 to 9.0 ± 1.1 cm) commensurate with reduction in stride length (1.9 to 1.7 m) and increased in stride width (7.7 0.2 cm to 9.0 ± 0.3 cm). Tibial angle in the frontal plane became more vertical at foot strike. Control of pelvic motion in all three planes significantly improves (pelvic drop decreased from 11.3 to 9.5 degrees, anterior-posterior rocking decreased by 1 degree and pelvic rotation decreased by 2 degrees). Trunk transverse rotation decreased from 14.3 to 12.7 degrees parallel, with small reductions in lateral oscillation of the center of gravity, indicating improved movement control. Average VALR decreased from 69.3 ± 24.2 to 44.6 ± 25.0 bodyweights/s. Knee flexion moments decreased, and peak hip moments in all three planes decreased. Finally, vertical stiffness increased from 154 ± 28 N/cm to 172 ± 30 N/cm. Collectively, this retraining produced a movement pattern that was less stressful on the musculoskeletal system.
Moving forward, we keep learning as scientists and clinicians. Patient feedback has been invaluable to us over time. Patients provide insight that it is helpful to start with high-impact cues first (cadence and fast, soft footfalls) followed by abdominal and gluteal activation. Big cues are followed by smaller cues. Often, the other healthy habits of more linear arm swing, slight anterior trunk lean, low bounce and head position naturally occur once these first directives are given. If not, cues are provided to tweak any remaining motions. In addition to directing cues for the healthy habits, runners are provided real-time video of their adjustment to the new form that they can take home and review. Finally, prepare the runner for the time frame of assimilating new running patterns and that form changes will feel foreign and require more central and metabolic effort initially.
**A final note is that these healthy running habits should be gradually introduced in intervals and smaller bouts to allow tissues to adapt. These habits should also be supported by regular participation in kinetic chain strengthening and neuromotor exercise, foot strengthening and mobility exercise.
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A strong running motion should be supported by a strong musculoskeletal system!