Massage and stretching causes a decrease in motor unit activation, while also increasing flexibility and decreasing perceived muscular pain (6). Fibrous adhesions are believed to occur from trauma at a micronized level during hard physical activity. These adhesions have been shown to inhibit typical mechanics of the muscle such as joint range of motion, muscle length, muscle coordination, and decreased strength and power production (1,4). Massage and similar techniques are believed to be effective in treating fibrous adhesions in the fascia (1).
A recent strategy to increase sports performance is a massage technique called myofascial release. This technique was created by Barnes (1) as a way to reduce fibrous adhesions that occur between layers of fascia/connective tissue (9). These fibrous adhesions are believed to be brought on by injuries, imbalances in the muscles, overrecruitment of muscle fibers, overworked muscles, recurring microtrauma, and inflammation (7). Areas of tightness in the muscles are generally referred to as myofascial trigger points and are defined as a “hypertensive palpable nodule or taut bands” of muscle tissue that is commonly found in the muscle belly (5). Myofascial release and massage techniques are used to break up these fibrous adhesions; but, the disadvantage of these techniques is that they generally are very time consuming with sessions lasting up to 90 minutes (12).
Self-myofascial release (SMR), a technique mimicking myofascial release is believed to have similar benefits as that of therapeutic myofascial release (9). However, the difference is that individuals performing SMR use their own body weight or leverage to apply pressure to the selected area. Foam rolling through the use of cylindrical tubes constructed of foam (foam rollers) has recently been introduced as part of training routines. Foam rollers, are placed on the floor and the individuals simply lays the thigh, buttocks, or back on the foam roller and moves back and forth applying pressure to the selected area.
Okamoto et al. (11) suggested that foam rolling restores muscles, tendons, ligaments, fascia, and soft-tissue extensibility. MacDonald et al. (9) concluded that SMR through smooth foam rollers enhanced knee joint range of motion (ROM); however, foam rolling had no effect on maximal knee extension force. Two additional studies (10,14) comparing static stretching, foam rolling, and foam rolling combined with static stretching on passive hip flexion found a significant (p = 0.001) change in ROM regardless of treatment. However, those receiving foam rolling and static stretching had a greater change than static stretch, foam rolling, or control.
Regarding performance, one study (7) compared planking with foam rolling and found no significant differences between the 2 treatments on the vertical jump (VJ) height and power, isometric force, or agility. However, foam rolling significantly reduced postexercise fatigue. Similarly, Sullivan et al. (15) found no significant effect on maximum voluntary muscle strength but significant increases in ROM for the sit-and-reach test after selected durations of foam rolling.
All current research has been conducted with smooth foam rollers. Recently, a new type of foam roller has become available (The Rumble Roller; STI, Baton Rouge, LA, USA), which will be described as a deep tissue roller (DTR). The difference between a regular smooth foam rollers and the DTR is that the DTR contains “high-profile” nodules that are semiflexible but firm and advertised as “much like the thumbs of a massage therapist.” The nodules have an asymmetrical shape and are spaced a little less than 50 cm apart and protrude about 10 cm from the surface of the roller on an alternating basis so that several of the nodules contact the body simultaneously. Thus theoretically, the DTR exerts more pressure because it does not contact a large surface area like a smooth roller. Although smooth foam rollers have been looked into, the aforementioned aggressive DTR rollers have yet to be investigated. Given the drastically altered surface of these rollers, it is possible that a protocol using the rollers may not result in similar findings as those using smooth rollers. To date, little information exists to evaluate these DTRs on certain performance variables. It is important to ascertain the effect of the DTRs on certain performance parameters so that coaches, trainers, and exercise enthusiasts can determine if and when to use them. The purpose of this study was to compare deep tissue rolling, dynamic stretch, and no intervention on VJ velocity and power, peak and average knee torque production, and hip ROM.
Experimental Approach to the Problem
The amount of effort and time to train these elite athletes are extensive and limited. Finding the best methods to achieve top physical conditioning is imperative. This study incorporated Division I football players and a new novel foam roller to ascertain the effect of its use on certain variables consistent with the sport. A random crossover design was used to compare selected physical variables. This study aimed to use a more aggressive foam roller (The Rumble Roller) equipped with raised nodules to allegedly stimulate deeper layers of muscle tissue and to stretch muscle and fascia in multiple directions. To our knowledge, no research exists that has used this particular type of foam roller to assess its effect on selected variables. Thus, the approach to this problem was to compare deep tissue foam rolling, dynamic stretch, and no intervention on lower body strength, power, velocity, and ROM.
Subjects were well-trained NCAA Division 1 football offensive linemen (n = 14) 18 years or older (range = 18–24 years) who had been competitive for more than 6 years in organized sports. Table 1 provides the physical characteristics of the subjects. The study took place in the off-season (summer), and all testing was done in the athletic facility. All subjects met with the researchers and were briefed on the requirements and objectives of the study and were informed of the benefits and risks of the investigation before signing an institutionally approved informed consent document to participate in the study. Additionally, subjects completed a health history questionnaire to ensure that the subjects qualified to participate in the study. Subject inclusion criteria consisted of no major lower extremity injury in the last year, not currently engaging in any stretching or flexibility program, free from any current injury or disease that could affect strength, power, or flexibility, and free of any circulation problems.
For the first or three visits, subjects reported to the weight room wearing athletic shorts, shoes, and a t-shirt. Assessments consisted of the recording of demographic information and anthropometric data (i.e., height and weight) of each participant. After these measures, each participant warmed up on a cycle ergometer for 5 minutes with a low resistance at 70 revolutions per minute. After the warm-up, each subject was pretested on VJ peak and average power and peak and average velocity, peak and average isometric knee flexion torque and extension torque, and hip flexion ROM. After pretesting, subjects were randomly assigned to one of 2 groups, either the DTR or dynamic stretch (DS) or no intervention. Deep tissue roller consisted of rolling on each extremity unilaterally for 1 minute (i.e., left and right hamstrings, left and right quadriceps, left and right gluteus maximus, and left and right gastrocnemius) for a total of 8 minutes. The DS protocol consisted of stretching the same muscles as those involved in the DTR protocol. Each stretch was formed slowly and under control to avoid a bouncing motion. Dynamic stretch stretching was coordinated to reflect equal time (8 minutes total) for each muscle group as with the DTR protocol. The no-intervention group remained inactive for the same amount of time. Immediately after treatment, postassessments were identical to the pretests. The second and third session was each scheduled exactly 1 week apart at the same time of day, and the groups were randomly assigned to a different treatment each session.
Power (in Watts) and velocity (in meters per second) assessments consisted of three counter movement VJs, whereas peak and average power and peak and average velocity data were collected by a Tendo Speed Analyzer (Tendo Sport Machines, M.R. Stefanika 19, 911 01 Trencin, Slovak Republic) connected to a laptop computer. The Tendo mat was placed on the floor, and a nylon cord from the device was then attached to a belt around the subjects' waist. After the VJ, all participants were assessed for hip flexion ROM using a Baseline Bubble Inclinometer (Fabrication Enterprises, Inc., White Plains, NY, USA). For testing, the subjects were supine on an examination able and their nondominant leg strapped to the table to avoid unwanted movement during the assessment. Next, a bubble inclinometer was zeroed and placed on the anterior thigh just above the knee, which was followed by the investigator passively stretching the hamstring by placing his left hand on the ankle and pushing the ankle toward the subject until a slight discomfort was felt and vocalized by the test subject. After the ROM assessments, the subjects underwent quadriceps and hamstring peak and average isometric torque measurements using a Biodex System 4 Pro dynamometer (Biodex Medical Systems, Shirley, NY, USA). Once the subjects were seated and strapped in the seat, the knee was positioned at a 60° angle and subjects were instructed to perform 3 warm-up repetitions for both knee extension and knee flexion at about 75% of their maximal effort. After the warm-up repetitions, the subjects waited 2 minutes and then underwent maximal testing. Testing consisted of 3 maximal knee extensions and flexion against the padded lever arm of the Biodex System.
All data were analyzed using IBM SPSS Version 21.0 Statistics (IBM Corporation, Armonk, NY, USA), and the main descriptive parameters were calculated (arithmetic mean and SD). To determine the statistical difference among the groups, repeated-measures analyses of variance (ANOVAs) were conducted. Post hoc analyses were conducted using Newman-Keuls post hoc measures. An alpha (α) level was set to p ≤ 0.05 to determine significance.
For peak VJ power, the DTR group and the DS group slightly outperformed the baseline assessment (2.1% vs. 0.8%, respectively); however, no significant (p = 0.45) differences were found among the groups (Table 2). Similarly, the repeated-measures ANOVA yielded no significant differences among the groups for average VJ power (p = 0.16) (Table 3). Regarding peak and average VJ velocity, neither dependent variable resulted in group differences (p = 0.0.25 and p = 0.23, respectively) (Tables 4 and 5).
No statistical significant differences were found for either peak knee extension isometric torque (p = 0.37) (Table 6) or average knee extension isometric torque (p = 0.62) (Table 7). Furthermore, no statistical significant differences were found for peak and average knee flexion isometric torque (p = 0.22 and p = 0.11, respectively). Interestingly, the baseline torques for both knee extension and knee flexion were greater than for either post-DTR or post-DS (Tables 8 and 9). For hip flexion ROM, both DTR and DS were significantly (p = 0.0001) greater than baseline measurements (Table 10). The DTR group demonstrated a 15.6% increase in hip flexion ROM, whereas the DS group posted a 19.9% increase.
These results conducted with a foam roller with “high-profile bumps” correlated with previous research that used smooth foam rollers or stretching before power, strength, and ROM assessments. For instance, the current results agree with others (7,9,15) in that both stretching and foam rolling may increase joint ROM similarly. Furthermore, the current results suggest that 8 minutes of DTR or DS had little impact on generation of power, velocity, or torque for knee extension and flexion. These finding are comparable with Healey et al. (7) who found no difference in isometric force production or VJ height after smooth foam rolling. These results were also similar to MacDonald et al. (9) who studied the effects of foam rolling on ROM, knee extension force, and muscle activation. The authors concluded that foam rolling had no effect on the force output of the quadriceps and no effect on muscle activation but found a significant positive effect on knee ROM (i.e., approximately 7–10° greater than the control). Additionally, the authors concluded that although foam rolling did increase knee ROM, there was no deficit in muscle performance. A similar study (3) concluded that foam rolling resulted in significant (p ≤ 0.05) gains in hip extension. Our study found similar results in that although foam rolling enhanced ROM, there was no detrimental effect of muscle force, power, or velocity. Another similar study used a small handheld device referred to as a roller-massager to assess its effects on ROM and maximal voluntary isometric contraction after rolling the hamstrings (15). The results showed a 4.3 and 2.3% increase in ROM of a sit-and-reach test after using the roller-massager for both 10 seconds and 5 seconds, respectively; however, there were no significant effects on maximal isometric contraction.
Regarding the effects of DS and VJ power production, Jaggers et al. (8) concluded that DS significantly increased VJ power production. In contrast, Jaggers et al. used healthy college-aged students, whereas our study used Division 1 college football linemen. Given the drastic body mass difference between varsity football players (offensive line = avg. 136 kg) and the general college male population, it is possible that these variances led to the difference in results. The rationale for an increased ROM after DTR has been addressed by many researchers who have suggested that deep tissue rolling has the ability to break down fibrous adhesions in the muscles and restore elasticity to the fascia (1,4,16). Our results also illustrate that both DTR and DS significantly increase ROM without a decrease in power and strength production. Deep tissue rollers could possibly be an alternative to static stretching that has been shown to increase ROM but also result in a stretch-induced performance deficit when used before activities that require strength and power (2,13).
A limitation of this study was the lack of experience by the subjects using this type of foam roller. The aggressive nature of this type of foam roller induces as a certain amount of discomfort. Given that the subject's weight plays a role in the amount of pressure exerted on the tissues, this could have a prompted the participants to attempt to reduce the pressure exerted on the roller, thus not gaining full benefit or detriment of the protocol.
Although the use of foam rollers do not appear to either benefit or deter maximal isometric strength or velocity, DTR does appear to enhance ROM and may be used in addition to traditional stretching exercises to maintain or increase ROM in athletes. As previously stated, DTR may be an appropriate substitute for static stretching because of the potential static stretch interference with the strength and power.
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