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Current Concepts in Periodization of Strength and Conditioning for the Sports Physical Therapist

Authors:  Lorenz D, Morrison S

The rehabilitation process is driven by the manipulation of training variables that elicits specific adaptations in order to meet established goals. Periodization is an overall concept of training that deals with the division of the training process into specific phases. Programming is the manipulation of the variables within these phases (sets, repetitions, load) that are needed to bring about the specific adaptations desired within a particular period The current body of literature is very limited when it comes to how these variables are best combined in an injured population since most of the periodization research has been performed in a healthy population. This manuscript explores what is currently understood about periodization, gives clinical guidelines for implementation, and provides the sports physical therapist with a framework to apply these principles in designing rehabilitation programs.

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Current Concepts of Muscle and Tendon Adaptation to Strength and Conditioning

Authors:  Brumitt J, Cuddeford T

Injuries to the muscle and/or associated tendon(s) are common clinical entities treated by sports physical therapists and other rehabilitation professionals.  Therapeutic exercise is a primary treatment modality for muscle and/or tendon injuries; however, the therapeutic exercise strategies should not be applied in a “one-size-fits-all approach”.  In order to optimize an athlete’s rehabilitation or performance, one must be able to construct resistance training programs accounting for the type of injury, the stage of healing, the functional and architectural requirements of the muscle and tendon, and the long-term goals for that patient.   The purpose of this clinical commentary is to review the muscular and tendinous adaptations associated with strength training, link training adaptations and resistance training principles for the athlete recovering from an injury, and illustrate the application of evidence-based resistance training for patients with a tendinopathy.

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Current Concepts of Plyometric Exercise

Authors:  Davies G, Riemann BL, Manske R

As knowledge regarding rehabilitation science continues to increase, exercise programs following musculoskeletal athletic injury continue to evolve.  Rehabilitation programs have drastically changed, especially in the terminal phases of rehabilitation, which include performance enhancement, development of power, and a safe return to activity.  Plyometric exercise has become an integral component of late phase rehabilitation as the patient nears return to activity.  Among the numerous types of available exercises, plyometrics assist in the development of power, a foundation from which the athlete can refine the skills of their sport. Therefore, the purpose of this clinical commentary is to provide an overview of plyometrics including: definition, phases, the physiological mechanical and neurophysiological basis of plyometrics, and to describe clinical guidelines and contraindications for implementing plyometric programs.

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Rolling Revisited: Using Rolling to Assess and Treat Neuromuscular Control and Coordination of the Core and Extremities of Athletes

Authors:  Hoogenboom BJ, Voight ML

Rolling is a movement pattern seldom used by physical therapists for assessment and intervention with adult clientele with normal neurologic function. Rolling, as an adult motor skill, combines the use of the upper extremities, core, and lower extremities in a coordinated manner to move from one posture to another. Rolling is accomplished from prone to supine and supine to prone, although the method by which it is performed varies among adults. Assessment of rolling for both the ability to complete the task and bilateral symmetry may be beneficial for use with athletes who perform rotationally-biased sports. When stability-based dysfunction exists, the rolling patterns can be used as intervention techniques, and have the ability to affect dysfunction of the upper quarter, core, and lower quarter. By applying proprioceptive neuromuscular facilitation (PNF) principles, the therapist may assist patients and clients who are unable to complete a rolling pattern. Examples given in the commentary include distraction/elongation, compression, and manual contacts to facilitate proper rolling. The authors assert that therapeutic use of the developmental pattern of rolling with techniques derived from PNF can be creatively and effectively utilized in musculoskeletal rehabilitation. Preliminary results from an exploration of the mechanism by which rolling may impact stability is presented, and available updated evidence is provided.  The purpose of this clinical commentary is to describe techniques for testing, assessment, and treatment of dysfunction, using case examples that incorporate rolling.

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Core Muscle Activity During The Clean and Jerk Lift With Barbell Versus Sandbags and Water Bags

Author:  Calatayud J, Colado JC, Martin F, Casaña J, Jakobsen MD, Andersen LL

While the traditional clean and jerk maneuver implies simultaneous participation of a large number of muscle groups, the use of this exercise with some variations to enhance core muscle activity remains uninvestigated. The purpose of this study was to compare the muscle activity during the clean and jerk lift when performed with a barbell, sandbag and a water bag at same absolute load.  There were no significantly significant differences for AD muscle activity between conditions, whereas muscle activation values for external obliques (60%MVIC), Gluteus medius (29%MVIC) and lumbar erector spinae (85%MVIC) were significantly higher during the water bag power clean and jerk maneuver when compared with the other conditions.  The authors concluded that the clean and jerk is an exercise that may be used to enhance core muscle activity. Performing the maneuver with water bags resulted in higher core muscle activity compared with sandbag and standard barbell versions.

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EMG Analysis and Sagittal Plane Kinematics of the Two-Handed and Single-Handed Kettlebell Swing: A Descriptive Study

Authors:  Van Gelder LH, Hoogenboon BJ, Alonzo B, Briggs D, Hatzel B

Kettlebell (KB) swing exercises have been proposed as a possible method to improve hip and spinal motor control as well as improve power, strength, and endurance. The purpose of this study was to describe electromyographic (EMG) and sagittal plane kinematics during two KB exercises: the two-handed KB swing (THKS) and the single-handed KB swing (SHKS). In addition, the authors sought to investigate whether or not hip flexor length related to the muscular activity or the kinematics of the exercise. Twenty-three healthy college age subjects participated in this study. Demographic information and passive hip flexor length were recorded for each subject. A maximum voluntary isometric contraction (MVIC) of bilateral gluteus maximus (GMAX), gluteus medius (GMED), and biceps femoris (BF) muscles was recorded. EMG activity and sagittal plane video was recorded during both the THKS and SHKS in a randomized order. Normalized muscular activation of the three studied muscles was calculated from EMG data. The authors found that during both SHKS and THKS, the average percent of peak MVIC for GMAX was 75.02% ± 55.38, GMED 55.47% ± 26.33, and BF 78.95% ± 53.29. Comparisons of the mean time to peak activation (TTP) for each muscle showed that the biceps femoris was the first muscle to activate during the swings.  Statistically significant (p < .05), moderately positive correlations (r = .483 and .417) were found between passive hip flexor length and % MVIC for the GMax during the SHKS and THKS, respectively. Therefore, the authors concluded that the THKS and SHKS provide sufficient muscular recruitment for strengthening of all of the muscles explored.  This is the first study to show significant correlations between passive hip flexor length and muscular activation of hip extensors, particularly the GMax.  Finally, the BF consistently reached peak activity before the GMax and GMed during the SHKS.

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The Effects of Self-Myofascial Release using a Foam Roll or Roller Massager on Joint Range of Motion, Muscle Recovery, and Performance: A Systematic Review

Authors:  Cheatham SW, Kolber MJ, Cain M, Lee M

Self-myofascial release (SMR) is a popular intervention used to enhance a client’s myofascial mobility. Common tools include the foam roll and roller massager. Often these tools are used as part of a comprehensive program and are recommended to the client for purchase and use at home. Currently, there are no systematic reviews that have appraised the effects of these tools on joint range of motion, muscle recovery, and performance.  The purpose of this review was to critically appraise the current evidence and answer the following questions: (1) Does self-myofascial release with a foam roll or roller-massager improve joint range of motion without effecting muscle performance? (2) After an intense bout of exercise, does self-myofascial release with a foam roller or roller-massager enhance post exercise muscle recovery and reduce delayed onset muscle soreness (DOMS)? (3) Does self-myofascial release with a foam roll or roller-massager prior to activity affect muscle performance?  A total of 14 articles met the inclusion criteria. SMR with a foam roll or roller massager appears to have short-term effects on increasing joint ROM without negatively affecting muscle performance and may help attenuate decrements in muscle performance and DOMS after intense exercise. Short bouts of SMR prior to exercise do not appear to effect muscle performance. The authors concluded that the current literature measuring the effects of SMR is still emerging. The results of this analysis suggests that foam rolling and roller massage may be effective interventions for enhancing joint ROM and pre and post exercise muscle performance. However, due to the heterogeneity of methods among studies, there currently is no consensus on the optimal SMR program.

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Eccentric and Concentric Jumping Performance During Augmented Jumps with Elastic Resistance:  A Meta-Analysis

Authors:   Aboodarda SJ, Page PA, Behm DG

The initial rapid eccentric contraction of a stretch-shortening cycle (SSC) activity is typically reported to accentuate the subsequent concentric jump performance. Some researchers have rationalized that adding elastic resistance (ER) to explosive type activities (e.g. countermovement jumps and drop jumps) would increase excitatory stretch reflex activity and mechanical recoil characteristics of the musculotendinous tissues. The purpose of this meta-analysis was to examine the available literature on jumping movements augmented with ER and to provide a quantitative summary on the effectiveness of this technique for enhancing acute eccentric and concentric jumping performance. The authors postulated that the excessive eccentric loading might trigger reflex inhibition, alter the muscle stiffness, increase downward hip displacement and dissipate mechanical recoil properties. These results suggest that the release of elastic force at the beginning of the concentric phase seems to be critical to avoid impairment of acute concentric performance in augmented jumps.

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Strength & Functional Assessment of Healthy High School Football Players: Analysis of Skilled and Non-Skilled Positions

Authors:  Paine R, Chicas E, Bailey L, Hariri T, Lowe W

Identifying an athlete’s functional capacity is an important consideration in determining when to allow an athlete to return to competition following injury. Establishing normative data for lower extremity functional assessment(s) is valuable for comparison when making decisions regarding the high school athlete returning to play after injury Therefore, the purpose of this study was to compare functional performance and strength between American high school football players of both skilled and non-skilled positions.  Forty-nine high school football players (30 skilled; 19 non-skilled) completed a single-session of testing consisting of Figure of 8 agility test (F-8), single-leg vertical jump (SLVJ), single-leg broad jump (SLBJ), and isokinetic knee strength assessment. Pearson correlation coefficients were used to determine the relationships between the results of functional testing and isokinetic strength measures. Paired t-tests were used to determine the differences in functional performance and isokinetic muscle strength between skilled and non-skilled athletes.  The authors found that knee extension peak torque/body weight (BW) was moderately correlated (p < .01) with SLBJ (r = .54-.61), SLVJ (r = .39-.48), and F-8 run times (r = -.50) for all athletes. Similar relationships were observed between knee flexion peak torque/BW and SLBJ (r = .48-.49), SLVJ (r = .28-.46), and the shuttle run times (r = .41-.52) for all subjects. No differences were observed between groups when examining raw peak torque values for knee flexion and extension (p > .05), however, skilled players did demonstrate greater peak torque/BW ratios (p < .05) for both knee extension and knee flexion at both tested speeds. Skilled players also displayed faster F-8 times (9.4 sec ± .3; p < .01) and greater SLBJ (p < .05) on both the dominant (81.0 in ± 9.3) and non-dominant (83.0 in ± 7.6) limbs (p < .01) when compared to non-skilled players.  Therefore the authors concluded that skilled football players displayed greater peak torque/BW ratios and functional performance when compared to non-skilled players. Furthermore, isokinetic peak torque/BW appears to be related to functional performance. This relationship is affected by position, with skilled players showing a stronger association. Limb dominance did not influence these functional and strength metrics. It is recommended that clinicians and coaches consider the positional differences in strength and functional performance when managing patients and athletes.

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Effects of a Dry-Land Strengthening Program in Competitive Adolescent Swimmers

Authors:  Manske R, Lewis S, Wolff S, Smith B

Shoulder pain is common in competitive young swimmers. A relationship between shoulder strength and shoulder soreness in competitive young swimmers may indicate need for strengthening in this group.  The purpose of this study was to determine if a shoulder exercise program would improve shoulder strength and decrease pain in competitive young swimmers.  Participants (10 control, 11 experimental) were randomly assigned to a control or experimental group. Strength was measured prior to the study for shoulder flexion, abduction, external rotation, internal rotation, and extension on the dominant arm using handheld dynamometry. The experimental group was then assigned exercises to be performed three times per week, for the twelve-week study period. The control group was instructed not to perform the exercises. All participants were re-tested at six and twelve weeks following initiation of the study. Changes in strength for each muscle group and pain were compared between groups using a mixed design two-way ANOVA. The authors found that the experimental group significantly increased external rotation strength compared to the control group. Shoulder soreness was not significantly different between groups.  The authors concluded that adolescents who performed shoulder strengthening significantly increased their external rotation strength compared to adolescents who only participated in a regular swimming regimen.

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Association of Isometric Strength of Hip and Knee Muscles with Injury Risk In High School Cross Country Runners

Authors:  Luedke LE, Heiderscheit BC, Williams DSB, Rauh MJ

High school cross country runners have a high incidence of overuse injuries, particularly to the knee and shin. Because lower extremity strength is modifiable, identification of strength attributes that contribute to anterior knee pain (AKP) and shin injuries may influence prevention and management of these injuries.  The purpose of this study was to determine if a relationship existed between isometric hip abductor, knee extensor and flexor strength and the incidence of AKP and shin injury in high school cross country runners.  Sixty-eight high school cross country runners (47 girls, 21 boys) participated in the study. Isometric strength tests of the hip abductors, knee extensors and flexors were performed with a handheld dynamometer. Runners were prospectively followed during the 2014 interscholastic cross country season for occurrences of AKP and shin injury. Bivariate logistic regression was used to examine risk relationships between strength values and occurrence of AKP and shin injury. The authors found that during the season, three (4.4%) runners experienced AKP and 13 (19.1%) runners incurred a shin injury. Runners in the tertiles indicating weakest hip abductor (chi-square = 6.140; p=0.046), knee extensor (chi-square = 6.562; p=0.038), and knee flexor (chi-square = 6.140; p=0.046) muscle strength had a significantly higher incidence of AKP. Hip and knee muscle strength was not significantly associated with shin injury.   Therefore, the authors concluded that in high school cross country runners with weaker hip abductor, knee extensor and flexor muscle strength had a higher incidence of AKP. Increasing hip and knee muscle strength may reduce the likelihood of AKP in high school cross country runners.

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Effectiveness of a Motor Control Therapeutic Exercise Program Combined With Motor Imagery on the Sensorimotor Function of the Cervical Spine: A Randomized Controlled Trial

Authors:  Hidalgo-Peréz A, Fernández-García A, López-de-Uralde-Villanueva I, Gil-Martínez A, Paris-Alemany A, La Touche R

Motor control therapeutic exercise (MCTE) for the neck is a motor reeducation program that emphasizes the coordination and contraction of specific neck flexor, extensor, and shoulder girdle muscles. Because motor imagery (MI) improves sensorimotor function and it improves several motor aspects, such as motor learning, neuromotor control, and acquisition of motor skills, the authors hypothesized that a combination of MCTE and MI would improve the sensorimotor function of the cervical spine more effectively than a MCTE program alone.  The purpose of this study was to investigate the influence of MI combined with a MCTE program on sensorimotor function of the cranio-cervical region in asymptomatic subjects.   The authors found that the combined MI and MCTE intervention produced statistically significant changes in sensorimotor function variables of the cranio-cervical region (highest pressure value, JPE extension and JPE left rotation) and the perception of subjective fatigue compared to MCTE alone. Both groups showed statistically significant changes in all variables measured, except for cranio-cervical neuromotor control and the subjective perception of fatigue after effort in the MCTE group

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Test-Retest Reliability of TETRAX® Static Posturography System in Young Adults with Low Physical Activity Level

Authors:  Akkaya N,  Do─čanlar N, Çelik E, Engin AS, Akkaya S, Güngör R, ┼×ahin F

Assessment of postural sway with force plates can be affected by type of measurement and various clinical parameters such as age and activity level of the individual. For this reason, variability is detected in postural reactions of healthy subjects without balance impairment. Test-retest reliability of postural sway in adolescent athletes has been measured using a force plate and additional test-retest studies have been suggested for subjects of different age groups with different activity levels.  Therefore, the purpose of this research was to assess test-retest reliability of Tetrax® Static Posturography System in young adults with low physical activity level, and examine the relationship between posturography results and activity level.   The results demonstrated the high test-retest reliability of Tetrax® interactive balance system in young healthy adults with low physical activity level. Future studies are needed to determine the effectiveness of increasing physical activity level on postural control.

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Effects of Normal Aging on Lower Extremity Loading and Coordination during Running in Males and Females

Authors:  Kline PW, Williams DSB

Runners frequently sustain injuries. As greater numbers of individuals continue to run past the age of 60, normal physiological changes that occur with aging may further contribute to injuries. Male and female runners demonstrate different mechanics and injury rates. However, whether these mechanics further diverge as runners age and whether or not this potential divergence in mechanics is associated with a potential for increased injury risk is unknown.  Therefore, the purpose of this study was to compare measures of loading and lower extremity coupling during running with respect to age and sex. It was hypothesized that males and females would demonstrate increasingly diverging mechanics with increased age.  Forty-one subjects were placed in four groups: younger males (n=13), younger females (n=6), older males (n=16), and older females (n=6). Ten running trials were collected and analyzed for each subject. Kinematic data were collected and reconstructed using a nine-camera motion analysis system and commercial software. Vertical loading rate (VLR), initial (GRF1) and peak vertical ground reaction force (GRF2) and lower leg joint coupling were calculated for each subject. Analysis was performed using a 2-factor ANOVA (sex X age) to determine differences between groups during the stance phase of running.  The authors found that compared to younger subjects, older subjects demonstrated higher GRF1 per body weight (Y: 1.70 (0.19), O: 1.96 (0.23), p< 0.01), higher VLR in body weight/second (Y: 44.17 (6.73), O: 52.76 (8.39), p< 0.01) and lower GRF2 per body weight (Y: 2.47 (0.18), O: 2.35 (0.18), p=0.04). However, no differences existed between males and females or further divergence of mechanics was seen in the older subjects. There were no differences between or within groups in joint coupling. Finally, no significant differences were seen between sexes and no interactions were found between any variables in the current study.  Therefore, the authors concluded that older runners experience greater GRF1 and VLR and lower GRF2. These are factors previously associated with tibial loading and stress fractures. Males and females do not differ on these factors suggesting older female runners may be at no greater risk than younger runners or male runners for lower extremity bony injury based on normal mechanics.  

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Ultrasound Imaging Measurement of the Transversus Abdominis in Supine, Standing, and Under Loading: A Reliability Study of Novice Examiners

Authors:  Hoppes CW, Sperier AD, Hopkins CF, Griffiths BD, Principe MF, Schnall BL, Bell JC, Koppenhaver SL

Military personnel and first responders (police and firefighters) often carry large amounts of gear. This load can negatively affect posture and lead to back pain. The ability to quantitatively measure muscle activation under loading would be valuable to clinicians to assess the effectiveness of core stabilization treatment programs and could aid in return to work decisions. Ultrasound imaging (USI) has the potential to provide such a measure, but to be useful it must be reliable. The purpose of this study was to assess the intrarater and interrater reliability of measurements of transversus abdominis (TrA) and internal oblique (IO) muscle thickness conducted by novice examiners using USI in supine, standing, and with an axial load. Healthy, active duty military (N=33) personnel were examined by two physical therapy doctoral students without prior experience in USI. Thickness measurements of the TrA and IO muscles were performed at rest and during a contraction to preferentially activate the TrA in three positions (hook-lying, standing, and standing with body armor). Percent thickness changes and intraclass correlation coefficients (ICC) were calculated.  Using the mean of three measurements for each of the three positions in resting and contracted muscle states, the intrarater ICC (3,3) values ranged from 0.90 to 0.98. The inter-rater ICC (2,1) values ranged from 0.39 to 0.79. The ICC values of percent thickness changes were lower than the individual ICC values for all positions and muscle states. The authors concluded that there is excellent intra-rater reliability of novice ultrasound technicians measuring abdominal muscle thickness using USI in three positions during the resting and contracted muscle states. However, inter-rater reliability of two novice technicians was poor to fair, so additional training and experience may be necessary to improve reliability.

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