Clinical Relevance of Foam Rolling on Hip Extension Angle in a Functional Lunge Position

Abstract

Bushell, JE, Dawson, SM, and Webster, MM. Clinical relevance of foam rolling on hip extension angle in a functional lunge position. J Strength Cond Res 29(9): 2397–2403, 2015—The objective of this study was to examine the duration of effectiveness of foam rolling on hip extension angles in a dynamic lunge position. Thirty-one subjects were assigned to control (n = 15) or intervention (n = 16) group. All the subjects followed the same testing timeline; 3 testing sessions, with 2 lunges in each session. The intervention group performed foam rolling between each lunge in sessions 1 and 2, and 5 times in 7 days between sessions 1 and 2. They did not foam roll during the week between sessions 2 and 3 or in session 3. The control group did not foam roll at all. Hip extension angles were recorded using Dartfish software and subjects filled out a global perceived effect scale rating the feeling of the second lunge and the intervention for each session. A 6 × 2 mixed-effects analysis of variance was run with post hoc t-tests revealing significant gains in hip extension within session 2 for the intervention group (p ≤ 0.05). Hip extension angles returned to baseline values after subject's ceased foam rolling for 1 week. Global perceived effect scores were higher for the intervention group and 29 of 32 words of descriptive feedback included positive words regarding foam rolling. We concluded that consistent foam rolling produced increases in hip extension during a dynamic lunge, but these effects are not seen within the first exposure. Foam rolling received positive reception and perceived improvements in hip extension. The findings indicate that repeated foam rolling is beneficial, both objectively and subjectively, for increasing range of motion immediately preceding a dynamic activity.

Introduction

Fascia is a constituent of connective tissue (¹²) and surrounds all organs and body structures. Myofascia directly envelops and connects muscles and forms chains, which are connected from the cranium through the toes (¹¹). Muscle imbalances or restrictions are common issues afflicting the musculoskeletal system and can lead to injury. Altered muscle function, imbalance, or restriction can arise when a muscle undergoes a change in its normal mechanics that can occur from tightness, weakness, injury, or overstress. These alterations cause shifts in the relationships between muscles because of a change in the neural firing. The ensuing imbalances lead to sheer stress on joints through muscle tone or atrophy and resultant pain to the muscle. When a muscle undergoes increased stress, the tissue suffers from breakdown and fatigue, which affects the myofascia locally and globally across the entire fascial chain (⁶).

One of the fascial chains that form a continuous meridian along the frontal plane of the body is the “superficial front line,” which has fascial connections between the scalp fascia, sternocleidomastoid, rectus abdominus, rectus femoris/quadriceps, subpatellar tendon, tibialis anterior, and short and long toe extensors. Restrictions in the superficial front line are seen with forward head posture, anterior pelvic shift and tilt, knee hyperextension, breathing restrictions in the anterior ribs, and ankle plantar flexion limitation (¹¹). Decreases in hip extension and backwards bending would be dysfunctional manifestations of these restrictions.

When fascia is negatively affected, it results in compensatory movement patterns, and its normal gel-like property hardens through the formation of fascial cross-links and scar tissue (^4,6,11). These formations inhibit proper biomechanics and reduce joint range of motion, causing pain, restricting muscle length, causing neuromuscular hypertonicity, decreased strength and endurance, and decreased motor coordination (⁶). Because myofascia is relatively superficial, it can be influenced through foam rolling (self-myofascial release), which helps to reduce these restrictions by remobilizing the tissue through friction and mechanical stress, helping to return the fascia into its original gel-like state (³). Foam rolling along part of the superficial front line can improve restrictions and range of motion.

Foam rolling may be a more effective modality for myofascial release over stretching and massage therapy because of its ability to increase range of motion without increasing potential for injury (^3,6,13). Stretching places tension and pressure on the origin and insertion of a muscle, which can cause damage to muscles by disrupting alignment of filaments or cross bridges, and tearing of sarcomeres (^6,8). When there is damage to muscle fibers, neuromuscular performance is hindered and the ability for the muscle to produce force is decreased (¹). Similarly, massage can create increases in range of motion, but subsequent detriments in muscle electromyography, strength, and motor neuron excitability have been reported (^6,13). Foam rolling is believed to enhance joint range of motion without these neuromuscular decrements as well as correct muscular imbalances and decrease muscle tone and spasm, alleviating muscle soreness and joint stress and thus promoting optimal skeletal function and neuromuscular efficiency (^3,4,6). There is evidence for foam rolling increasing hip extension as an isolated movement for a short period (⁶). What has yet to be investigated is if foam rolling the anterior thigh will still cause improvements in hip extension when stretch is placed on the rest of the frontal plane or if the range of motion gained transfers to dynamic movement.

Increases or decreases in range of motion can be tested passively or in a functional dynamic movement. However, changes in passive motion do not necessarily transfer to improvements in functional range of motion. This is likely contributable to multiple motor patterns and muscle groups being used in a dynamic movement. The body develops patterns of movements throughout one's life. These patterns develop as the most energy efficient way for that individual to perform a movement (¹⁰). Researchers investigating a 6-week stretching, myofascial release, and hip/spine dissociation exercise intervention report improvements in hip extension only in the position they stretched in, with no transfer to dynamic activities such as lunging, walking, and running (^8,10).

Individuals of all levels of sport and injury use foam rolling; foam rollers are readily available to the general public and athletes of all levels. Many clinicians and health care professionals prescribe foam rolling for their patients for any number of muscle-related injuries, general soreness, recovery, or prevention. However, there is a lack of consistency and evidence-based practice behind the reasoning people are choosing to foam roll (FR).

It is important to understand if foam rolling has a direct effect on the area that is treated and if so, how long the effects of foam rolling can be maintained by the body. Humans move dynamically on a daily basis, parameters for improving their function are important to determine appropriate return to activity guidelines or the time of day to implement rehabilitation interventions. Because fascia is a chain, and overlies muscles that work in relationships, we were interested in determining whether foam rolling the anterior thigh, a larger area of the superficial front line would cause improvements in hip mobility when the rest of the chain was put on stretch and if these gains in hip extension achieved through foam rolling would transfer to a functional movement pattern such as the lunge. To the best of our knowledge, there are no studies exploring the effects of foam rolling on increasing extensibility in a dynamic position, and none that examine whether a prolonged FR intervention will allow for greater gains in hip extension or if improvements will be maintained 1-week postintervention. With the popularity of foam rolling and its use as a rehabilitation intervention patient-based outcomes and intervention parameters are important to establish for both clinicians and individuals self-use.

The purpose of this study was to determine whether foam rolling the anterior thigh can increase the range of motion in hip extension in a dynamic lunge position and if these changes will remain 1-week postintervention.

Hypotheses

• The intervention (FR) group will have increased hip extension, compared with the control group, immediately after 1 session of foam rolling, as well as after 1 week of foam rolling, but will return to prestudy baseline values after ceasing foam rolling for 1 week.
• The intervention group will report a higher score on the global perceived effect (GPE) scale immediately after 1 session of foam rolling, and after 1 week of foam rolling, compared with the control group.

Methods

Experimental Approach to the Problem

The study design used foam rolling and the concept of fascia as a continuous chain in the superficial front line (Figure 1) to determine whether foam rolling the anterior portion of the thigh caused increases in hip extension in an active movement such as the lunge (Figure 1) (¹¹). The lunge position was chosen as it is a functional position for physical activity compared with passively testing a single joint angle in a seated or lying position. To determine whether the previously reported gains in hip extension from foam rolling (^6,8) transferred to a dynamic activity, we tracked hip extension angle while subjects performed a lunge. Subjects performed 2 lunges during 3 sessions 1 week apart to test if foam rolling produces immediate and lasting effects on hip extension angle. To do this, we incorporated 2 independent variables. The first was a subject group, a between-subjects qualitative variable with 2 levels; control and intervention (FR). We had a control group to ensure that any increases in hip extension were due to foam rolling and not due to a warm-up effect from repeated lunging alone. The second independent variable was the testing session, a within-subjects measure with 6 levels; a pre- and postmeasurement at each of the 3 sessions. The first quantitative dependent variable was hip extension angle. The final dependent variable was the GPE score, which was incorporated to better understand how the subjects felt about their treatment.

Figure 1: Example of the lunge position.

Subjects

Thirty-three subjects were recruited from a University campus through e-mail and word of mouth. Two subjects did not complete the study, 1 due to injury and the other due to schedule conflicts, resulting in a total of 31 participants completing the study. Nineteen men and 12 women ranging from 18–28 years participated with a mean age of 21.35 ± 2.44 years, a mean weight of 74.96 ± 10.21 kg for men and 62.79 ± 7.72 kg for women, and a mean height of 178.36 ± 6.35 cm for men and 165.93 ± 7.18 cm for women. All subjects reported a minimum of 1.5 hours of physical activity per week (a mean of 9.02 ± 5.79 hours) and had not performed foam rolling within the last 4 months. Subject backgrounds were 2 Nordic skiers, 15 triathletes, 9 recreational athletes, 4 elite tennis players, and 1 swimmer with respective means of 10.75, 9.5, 3.11, 20, and 6 hours of physical activity a week. Subjects training backgrounds ranged from varsity competitive athlete with 10–21 hours of training a week to recreational athletes averaging 3 hours of intense physical activity a week. Subjects were tested in either November or January and assigned to the control (n = 15) or the intervention/FR (n = 16) groups. No subject had any current injury that affected their ability to lunge or FR. Subjects were asked to indicate which leg they would kick a ball with, and this leg became the tested extremity with that hip being extended during the lunge. Twenty-nine of the subjects tested their right hip, and 2 tested the left. All subjects followed the same testing protocol and written informed consent was signed and obtained from the subject. All subjects were tested on a hard tile surface in the same location. There was no restriction on participants' nutrition, hydration or workout type, time of day, intensity, length or frequency, aside from the imposed minimums to be a subject in the study. The University's Institutional Review Board approved this study.

Procedures

Independent Variables

Testing Session

Subjects were tested over the course of 3 weeks, with each session occurring exactly 1 week from their previous session at the same time and same location at the University of Oregon. Sessions were labeled sequentially with session 1 being the first session, session 2 occurred the next week, and session 3 the following week from session 2. At the start of each testing session, subjects filled out a questionnaire including demographic information, the number of hours of physical activity performed that week, and any new or current injuries. In session 2, the intervention group also recorded their self-reported minutes and days they had foam rolled that week. Markers were placed on anatomical landmarks on the dominant side of the body on the acromion process, greater trochanter, lateral femoral condyle, and lateral malleolus. In addition, markers were added to the contralateral medial femoral condyle and medial malleolus. Subjects were shown how to perform the extended lunge and allowed to practice it once (Figure 1) at the start of each session before beginning the protocol.

All subjects placed their nondominant foot at a designated marking and were instructed to keep that knee bent to 90° while keeping their tested extremity as straight as possible behind them, with the heel on the ground. Once in this position they were asked to lean back as far as possible with their arms over their head, not changing their leg positions, and then finally to drop the arm of the same side as their tested leg down to their side. All subjects performed 2 lunges during each session.

Subject Groups

Intervention Group—Foam Roller and Foam Rolling Technique

Intervention subjects foam rolled on a 12 × 6 inch foam roller composed of expanded polyethylene high-density foam. This type of foam roller was chosen because of its effectiveness examined in previous literature (^3,6) and its accessibility to subjects. We also made several foam rollers of this type available to our participants 20 hours each day in an accessible locker in the lobby of the University of Oregon Student Recreation Center.

For the myofascial foam rolling technique, the intervention subjects were instructed to begin in a plank position and place the foam roller on their anterior thigh of the dominant (tested) leg at the most proximal part of the quadriceps muscle, just inferior to the anterior superior iliac spine. They then walked themselves forward using their hands or forearms so the foam roller rolled down the length of the quadriceps. They were instructed to stop rolling forwards when the foam roller reached the top of their knee and to reverse the direction so the foam roller returned to the start position. They were instructed to repeat this motion for three 1-minute bouts with 30 seconds of rest between each minute. This timing was chosen based on previous studies, which demonstrated that a continual pressure for 60–90 seconds was optimal for myofascial release (^6–8). Subjects were allowed to place their nontesting extremity on top of the extremity they were foam rolling or, if the pressure was too great, they were able to place the nontesting extremity on the ground to relieve some of the weight on the foam roller. Subjects then immediately performed their second lunge. The intervention group performed foam rolling between the lunges of sessions 1 and 2 and for 5 separate unsupervised sessions occurring on different days of this same 3 × 1 minute bout of rolling in the week between sessions 1 and 2.

The control group did not perform any foam rolling and was instructed to sit quietly for 3 minutes between their 2 lunges. Both groups were told to keep their weekly activity consistent with before beginning the study, with the added excepting, the intervention group added foam rolling into their weekly routine.

Measurements

Video

Subjects were video recorded using a standard Sony handycam mounted on a tripod at 12 feet from the participant. This distance was kept consistent at each session and enabled the testers to view the subject's entire body. The background was a plain white wall with no markings. Subjects were given verbal feedback and encouragement during each lunge to help ensure proper positioning.

The video of each subjects lunge was transferred to the Dartfish software program (Atlanta, GA, USA). On Dartfish, the same tester measured hip extension angle, relative to the nondominant thigh by drawing vectors onto the video. The video was then played, and hip extension angle was tracked by this drawn angle.

At the start of each lunge, the subjects lined up the distal end of their first hallux of their forward, nontested foot to a line that was taped at 80 cm from a reference point. This was done to ensure accuracy and consistency of foot spread within and between subjects and sessions. We also did this for any calibration in measurements that Dartfish software may have required, such as foot spread.

Dependent Variables

Hip Extension Angle

The vectors were drawn beginning at the greater trochanter of the dominant leg to the lateral femoral condyle of the same leg and the contralateral medial femoral condyle. We recorded the largest angle indicating the deepest part of the lunge was achieved.

Global Perceived Effect Scale

After each session, all subjects filled out 2 GPE scales by circling a number on the scale ranging from −5 to +5: −5 equivocated to much worse, 0 was no change, and +5 indicated much improvement. Kamper et al. (⁵) reported excellent test-retest reliability and reliable assessments of perceived and actual changes in people with musculoskeletal disorders using this tool. Subjects circled 2 scales, 1 to report how they felt performing their second lunge compared with the first lunge of the current session and a second to indicate how they felt foam rolling (intervention group) or resting (control group). Subjects were unaware as to their recorded values of hip extension in each lunge; this ensured no bias toward their ratings of foam rolling. During session 3, the second GPE scale question was changed to ask how the intervention group felt resting this week compared with the week they performed foam rolling. Finally, subjects also wrote down 2 words to describe how their tested extremity felt after the testing session. Before analysis, these words were grouped into 3 categories; positive, no change, or negative.

During the week between sessions 1 and 2, the intervention group repeated the foam rolling treatment 5 separate times for 3 minutes with 30-second rest between each minute of treatment. Foam rollers were made available to the subjects in the student recreation center, or they could use their own uniform polystyrene roller. The control group was asked not to alter their normal physical routines. After session 2, the intervention group was asked to stop using a foam roller for the week between sessions 2 and 3 but continue with their normal physical activity routine. When subjects returned for session 3, the protocol remained the same as the previous 2 testing sessions, but neither group performed foam rolling between their 2 extended lunge positions.

Statistical Analyses

Hip extension data were analyzed using a mixed-effects analysis of variance (ANOVA) with 2 levels of between-subject and 6 levels of within-subject variables. Post hoc paired samples t-tests were then run, when appropriate, based on results of the ANOVA. A univariate ANOVA was run to determine effect size and test-retest reliability. Significance level was chosen at α = 0.05.

Results

Hip Extension

We hypothesized that the intervention group would have increased hip extension, compared with the control group, immediately after 1 session of foam rolling and after 1 week of foam rolling. A mixed-effect ANOVA revealed that there were no significant increases in hip extension angle between the control group and intervention group immediately or across time for all 6 lunges (f < 1, p > 0.05). In contrast, within-group differences were identified (f = 6.08, p = 0.00) within the intervention group. Post hoc t-tests determined that there were significant increases in hip extension within session 2 (p ≤ 0.05; effect size: r = −0.11) for the intervention group. After 1 week of foam rolling, we expected increases in hip extension angle to be present at the start of session 2. Instead, only significant increases in hip extension angle occurred within session 2. Both pre- and postlunge mean hip extension angles in session 3 did not differ significantly from session 1 baseline lunge (p > 0.05), supporting our hypothesis that the effects of foam rolling on the body are not maintained long term after the intervention stops (Figure 2).

Figure 2: Mean amount of hip extension angle of pre- and postlunge in each session within each subject group.

Globalized Perceived Effect Scores

We added all numbers circled on the GPE scale for each question at each session to create a total score for the intervention and control groups. More positive feelings were expressed toward foam rolling compared with resting in session 1 (intervention = +31, control = +17) (p = 0.08, 95% confidence interval [CI]: −1.87 to 0.13, r = 0.98). After 1 week of intervention, the positive feelings were significantly greater than the control group (intervention = +48, control = +15; Figure 3A) (p = 0.00, 95% CI: −1.14 to −4.97, r = 0.10). Score improvements performing the postlunge are reported during session 2 by the intervention group (intervention = +34, control = +18; Figure 3B), although they do not demonstrate significance (p = 0.20, r = 0.98). After ceasing foam rolling for the second week, the intervention group reported feeling significantly worse while performing a lunge compared with the week they were allowed to FR, +5 and +48, respectively (p = 0.00, 95% CI: −4.11 to −1.26, r = −0.10). The control group feelings remained relatively similar to the previous sessions, +11 and +15, respectively. These reports partially support our hypothesis; higher scores are achieved on the GPE scale with the addition of foam rolling, although a significant increase in scores only occurred after a week of intervention.

Figure 3: Global perceived effect scores on how subjects feel after foam rolling or resting (A) and on performing the postlunge compared with the prelunge (B). GPE scale is a range from −5 to +5. GPE score was calculated by adding the reported scores by a group, within a session.

Discussion

Foam rolling is often used in sport and recreation settings as an alternative to stretching or massage to achieve improved recovery from workouts, increases in range of motion, and as a warm-up for muscles and fascia. It was developed as a way to allow the patient to provide self-release and mobilization of tissue. Past research indicates that preactivity static stretching and massage are potentially detrimental by causing over stretch to muscle tendons or dampening motor neuron excitability (^1,3,6,13). Foam rolling is thought to produce an increase in range of motion and warm-up the tissues without the subsequent decrements found in stretching and massage (^6,7). Range of motion improvements from a 6-week intervention of stretching and hip/spine dissociation exercises did not transfer to functional movements such as elliptical training, twist and reach, standing active hip extension, and lunging (¹⁰). Therefore, we developed this study to examine foam rolling used as a warm-up before activity to aid in increasing range of motion in the dynamic movement of a lunge. To the best of our knowledge, this is the first peer-reviewed study to investigate whether any increases in range of motion caused by foam rolling will transfer to functional movement. Within the intervention group who foam rolled, significant increases in hip extension angle were gained in the postlunge compared with the prelunge of session 2 after 1 week of FR intervention. Surprisingly, the prelunge of session 2 did not have significantly larger hip extension angles than session 1, despite foam rolling 5 times that week.

We expected increases in hip extension angles after 1 week of foam rolling in the prelunge of session 2. Instead, no significant change in mean hip extension angle occurred compared with the respective lunges in session 1. However, noting the significant gain in hip extension in the intervention group from prelunge to postlunge in the second session and comparing them to the results reported by Macdonald et al. (⁶) of immediate gains in knee flexion angle post foam rolling, it is reasonable to conclude that the effects of foam rolling are immediate, even in a dynamic movement, but do not remain for longer bouts of time. This is supported by a previous study printed in the Journal of Undergraduate Research investigating foam rolling across multiple weeks. They report no gains in hip flexion range of motion from foam rolling the hamstrings for 8 weeks (⁹), indicating that effects of foam rolling are neither cumulative nor last over longer periods of time.

Therefore, the first hypothesis that the intervention group would have larger gains in hip extension compared with the control group immediately and after 1 week of foam rolling can be partially rejected as significant gains in hip extension were shown within the intervention group but not between groups. Although these results are not significant, the intervention group gained a mean of 3.70° in hip extension compared with 0.34° in the control group. One reason why no statistical difference existed between groups could be the magnitude of individual variability. The variance in each group is larger than their gains in hip extension, thus reducing the statistical likelihood of identifying differences between groups. Reasoning for the intervention subjects not achieving significant gains in hip extension after foam rolling in session 1 compared with session 2 can be attributed to the initial exposure of foam rolling. Many of our subjects had never foam rolled before and the others had been more than 4 months without exposure. This first experience can be uncomfortable and even painful, as the pressure exerted by the foam roller on the anterior thigh is 33.4 kPa (³). The intervention group had 8 subjects who use negative words such as “sore” to describe how they felt after foam rolling in the first session, which reduced to only 3 subjects in the second session. Feelings of soreness and exposure to a new stress on the body can affect the feeling of extensibility while performing the postlunge. Larger gains seen within the intervention group in the second session could be credited to repeated exposure to the stimulus, which will dampen the subjects' sensitivity to it. Therefore, recurrent bouts of rolling throughout the week may have allowed individuals to accommodate to the pressure of the roller by dulling the sensation of the stretch end point through pressure on cutaneous receptors (⁶). This allows for improved performance in the postlunge when the subjects returned for the second session.

Our hypothesis that hip extension values in the intervention group will return to prestudy baseline values after ceasing foam rolling for 1 week can be accepted as there is no significant change between session 3 and session 1 prelunge in the intervention group (p > 0.05). The control groups mean hip extension values never differed more than s = 1.65° across all session (p > 0.05). These values indicate that any increases in hip extension angle are solely due to foam rolling and not due to repeated lunging.

Subjects GPE scores support part of our hypothesis that the intervention group will report higher scores compared with the control group; however, the scores were only significantly higher in the second session (p = 0.00) indicating that they felt much better after repeated exposure to foam rolling. This lends effectiveness to foam rolling, despite no significance in the objective measures between groups; significance in subjective measures supports the use of foam rolling as there is a large aspect of mental preparedness in sport and physical activity. If a patient perceives a treatment as improving their physical movement or range of motion, it is considered an effective treatment.

The words subjects wrote down during each session further support the subjective positivity toward foam rolling as a warm-up tool. Of the 32 words reported by the intervention group, 29 reflect positive feelings toward subjects foam rolling experience, compared with only 12 positive words reported by the same subjects once they ceased foam rolling for the third session. Subjects used words such as “stretched,” “relaxed,” and “long” to describe foam rolling, and “stiff” or “sore” to describe the week without foam rolling.

Future studies could further investigate the pre- vs. postactivity effectiveness. It is important to keep in mind foam rolling likely has its largest gains in softer myofascial structures, because the amount of force needed to produce a 1% change in dense fascia is far outside the human physiological range (²). Therefore, actual tissue deformation would be painful and unachievable by foam rolling alone. Softer tissues could be deformed with forces at the upper bounds of the physiological limits (²).

Reasoning for lack of significance between subject groups can be attributed to testing hip extension angles in a dynamic position as opposed to passive. Moreside et al. (¹⁰) discovered that subjects did not use passive gains in hip extension when tested performing a lunge and instead tried to gain the motion with other body segments such as lumbar extension. This suggests that preexisting motor patterns seem to dominate over gains in range of motion achieved in other ways. A limitation to our study is we did not put restrictions on how subjects moved to achieve the lunge; subjects were in a free-standing dynamic position guided only with verbal cues. They may have been more focused on these cues than on hip extension, and their pre-engrained motor patterns could have prevented increases in hip extension. Significant gains in knee range of motion reported in previous studies may be more achievable because they used a strict, hip fixed, kneeling position in a modified lunge (^6,7), so there was little room for subjects' prelearned movement pattern to be used.

Another limitation is that it is possible that there was bias toward foam rolling being effective, which may have influenced the positivity toward foam rolling. Because foam rollers are present in many gyms and athletic training rooms, subjects may have preconceived notions of foam rolling being beneficial. Global perceived effect scores may permit excessive between test variability as shown by the correlation coefficient r = 0.10. Other limitations lie in the type of foam roller used, previous peer-reviewed literature used polyvinyl chloride pipe with neoprene surrounding it, whereas our subjects rolled on polystyrene foam rollers, chosen for accessibility and cost. We recognize that greater effects may have been demonstrated with a harder foam roller because of the pressure and force it exerts on soft tissue (³).

Another large limitation exists in not controlling subjects' physical activity during the testing days. Therefore, subjects could have been sedentary all day or have come from a workout session of any varying type of activity. Because of dynamic movement and nonsimilar workout habits, large SDs and lack of significance from control preclude statistical and biological significance. Although we had a larger subject pool than previous FR studies, testing a dynamic movement requires a larger subject number to increase effect size and statistical power, which will account for individual variability with movement within a session and across multiple days.

Practical Applications

The increases in hip extension observed in a lunge immediately after foam rolling and after repeated exposure support the use of foam rolling as a prephysical activity and warm-up modality. Regardless of the degree or range of motion an individual may achieve, subjective positivity reported with foam rolling give evidence to support implementing foam rolling to achieve increases in hip extension range of motion before physical activity. It is self-administered and can be modulated by the individual with little instruction from a therapist and can be performed at the site of physical activity on a daily basis, allowing therapists more hands on time with the athlete. This gives the patient or athlete a sense of control over their warm-up or treatment.

Acknowledgments

The purchase of the 4 foam rollers for use by our subjects was provided by the Department of Human Physiology at the University of Oregon. No other funding was required for this study. The authors thank Sierra Dawson, manuscript supervisor, and mentor for helping the research question take shape into a feasible study, Margaret Webster, research assistant, who helped to carry out all subject testing and computing of data, and Jake Mahon who provided his knowledge of statistical analysis so that the appropriate statistical tests were used and the results are honest. The authors also thank the subjects for donating their time to allow the study to be completed. There are no professional relationships with companies or manufacturers who will benefit from the results of this study. The results of this study do not constitute endorsement by ACSM or of any particular company or producer for the materials used in this study.