Steven R. Murray

High-risk stress fractures: pathogenesis, evaluation, and treatment.

High-risk stress fractures require precise assessment and treatment because of their propensity for delayed union, nonunion, or complete fracture and their resulting disabling complications. Proper diagnosis necessitates a thorough clinical evaluation, centering on the patients diet and history, particularly the training regimen. For a definitive diagnosis, plain radiography, ultrasound, bone scintigraphy, magnetic resonance imagery (MRI), and computed tomography (CT) are helpful, and each plays a specific role. High-risk stress fractures typically require aggressive treatment such as nonweight-bearing immobilization coupled with therapy and often surgery.

Effect of hang cleans or squats paired with countermovement vertical jumps on vertical displacement.

Andrews, TR, Mackey, TA, Inkrott, TA, Murray, SR, Clark, IE, and Pettitt, RW. Effect of hang cleans or squats paired with countermovement vertical jumps on vertical displacement. J Strength Cond Res 25(9): 2448-2452, 2011—Complex training is characterized by pairing resistance exercise with plyometric exercise to exploit the postactivation potentiation (PAP) phenomenon, thereby promising a better training effect. Studies on PAP as measured by human power performances are equivocal. One issue may be the lack of analyses across multiple sets of paired exercises, a common practice used by athletes. We evaluated countermovement vertical jump (CMJ) performance in 19 women, collegiate athletes in 3 of the following trials: (a) CMJs-only, where 1 set of CMJs served as a conditioning exercise, (b) heavy-load, back squats paired with CMJs, and (c) hang cleans paired with CMJs. The CMJ vertical displacement (3-attempt average), as measured with digital video, served as the dependent variable of CMJ performance. Across 3 sets of paired-exercise regimens, CMJ-only depreciated 1.6 cm and CMJ paired with back squats depreciated 2.0 cm (main effect, p < 0.05). Conversely, CMJ paired with hang cleans depreciated 0.30 cm (interaction, p < 0.05). Thus, the best complex training scheme was achieved by pairing CMJs with hang cleans in comparison to back squats or CMJs in and of themselves. Future research on exercise modes of complex training that best help athletes preserve and train with the highest power possible, in a given training session, is warranted.

Avulsion fracture of the iliac crest apophysis in a collegiate wrestler.

INTRODUCTION Fractures of the pelvic girdle along the iliac crest, although rare, have been documented since the mid-1700s. The pelvic girdle is made up of two coxal bones that are joined anteriorly at the symphysis pubis and posteriorly to the sacrum; the two coxal bones join with the sacrum and coccyx to form the pelvis. The pelvis provides protection for internal organs, attachments for muscles, and stable support of the lower extremities to enable locomotion. Although fractures of the iliac crest are rare, they typically occur in individuals aged 11–25 years because of incomplete ossification of the apophyses in the pelvis, with males having an incidence rate 13 times that of females. The mechanism of injury is commonly a rapid, forceful eccentric lateral flexion and/or rotation of the torso causing excessive strain of the abdominal musculature. The tensile force exceeds the strength of the apophysis of the iliac crest, resulting in an avulsion. Fortunately, because of the numerous muscle attachments of the pelvis, bone displacement is minimal, and surgical intervention is often unnecessary. Avulsion fractures of the iliac crest are rare, making up roughly 2% of all pelvic fractures. To our knowledge, no case has been reported regarding an avulsion fracture from wrestling, making our patient’s case unique.

Dynamic Compression Enhances Pressure-to-pain Threshold in Elite Athlete Recovery: Exploratory Study

Abstract Sands, WA, McNeal, JR, Murray, SR, and Stone, MH. Dynamic compression enhances pressure-to-pain threshold in elite athlete recovery: exploratory study. J Strength Cond Res 29(5): 1263–1272, 2015—Athlete recovery-adaptation is crucial to the progress and performance of highly trained athletes. The purpose of this study was to assess peristaltic pulse dynamic compression (PPDC) in reducing short-term pressure-to-pain threshold (PPT) among Olympic Training Center athletes after morning training. Muscular tenderness and stiffness are common symptoms of fatigue and exercise-induced muscle microtrauma and edema. Twenty-four highly trained athletes (men = 12 and women = 12) volunteered to participate in this study. The athletes were randomly assigned to experimental (n = 12) and control (n = 12) groups. Pressure-to-pain threshold measurements were conducted with a manual algometer on 3 lower extremity muscles. Experimental group athletes underwent PPDC on both legs through computer-controlled circumferential inflated leggings that used a peristaltic-like pressure pattern from feet to groin. Pressures in each cell were set to factory defaults. Treatment time was 15 minutes. The control group performed the same procedures except that the inflation pump to the leggings was off. The experimental timeline included a morning training session, followed by a PPT pretest, treatment application (PPDC or control), an immediate post-test (PPT), and a delayed post-test (PPT) after the afternoon practice session. Difference score results showed that the experimental groups PPT threshold improved after PPDC treatment immediately and persisted the remainder of the day after afternoon practice. The control group showed no statistical change. We conclude that PPDC is a promising means of accelerating and enhancing recovery after the normal aggressive training that occurs in Olympic and aspiring Olympic athletes.

Do the Noncaffeine Ingredients of Energy Drinks Affect Metabolic Responses to Heavy Exercise

Abstract Pettitt, RW, Niemeyer, JD, Sexton, PJ, Lipetzky, A, and Murray, SR. Do the noncaffeine ingredients of energy drinks affect metabolic responses to heavy exercise? J Strength Cond Res 27(7): 1994–1999, 2013—Energy drinks (EDs) such as Red Bull (RB) are marketed to enhance metabolism. Secondary ingredients of EDs (e.g., taurine) have been purported to improve time trial performance; however, little research exists on how such secondary ingredients affect aerobic metabolism during heavy exercise. The purpose of this study was to investigate the effect of the secondary ingredients of RB on aerobic metabolism during and subsequent to heavy exercise. In double-blind, counterbalanced, and crossover fashion, 8 recreationally trained individuals completed a graded exercise test to determine the gas exchange threshold (GET). Subjects returned on 2 separate occasions and ingested either a 245 ml serving of RB or a control (CTRL) drink with the equivalent caffeine before engaging in two 10-minute constant-load cycling bouts, at an intensity equivalent to GET, with 3 minutes of rest between bouts. Accumulated liters of O2 (10 minutes) were higher for the first bout (17.1 ± 3.5 L) vs. the second bout (16.7 ± 3.5 L) but did not differ between drinks. Similarly, excess postexercise oxygen consumption was higher after the initial bout (RB mean, 2.6 ± 0.85 L; CTRL mean, 2.9 ± 0.90 L) vs. the second bout (RB mean, 1.5 ± 0.85 L; CTRL mean, 1.9 ± 0.87 L) but did not differ between drinks. No differences occurred between drinks for measures of heart rate or rating of perceived exertion. These results indicate that the secondary ingredients contained in a single serving of RB do not augment aerobic metabolism during or subsequent to heavy exercise.

APPLYING THE CRITICAL VELOCITY MODEL FOR AN OFF-SEASON INTERVAL TRAINING PROGRAM

Abstract Clark, IE, West, BM, Reynolds, SK, Murray, SR, and Pettitt, RW. Applying the critical velocity model for an off-season interval training program. J Strength Cond Res 27(12): 3335–3341, 2013—The critical velocity (CV) model offers an opportunity to prescribe and to test empirically different velocity-time (V–t) configurations of high-intensity interval training (HIIT); however, such experiments are lacking. We evaluated a group of competitive, female soccer players (age = 19 ± 1 years, height = 168 ± 6 cm, mass = 61 ± 6 kg) completing 1 of 2 different HIIT regimes: a short group (n = 6) completing higher V and shorter t configurations, and a long group (n = 10) completing lower V, longer t configurations. Both groups trained 2 d·wk−1 for 4 weeks. For each workout, both groups ran at velocities exceeding CV and designed to deplete identical fractional percentages of the finite work capacity above CV (D′). The metrics of CV and D′ were evaluated at pretraining and posttraining using the 3-minute all-out exercise test on an indoor track using video digitizing of displacement relative to time. Despite differences in the V–t configurations, both groups increased their CV (+0.22 m·s−1, +6%) and decreased their D′ (−24 m, −13%; p < 0.05). We conclude that 2- to 5-minute HIIT bouts are suitable for increasing CV, in previously trained athletes, but they result in a decline of D′. To increase D′, we suggest examining HIIT of intensities that are <2 minutes and >130% of maximum oxygen uptake.

Peristaltic pulse dynamic compression of the lower extremity enhances flexibility.

Abstract Sands, WA, Murray, MB, Murray, SR, McNeal, JR, Mizuguchi, S, Sato, K, and Stone, MH. Peristaltic pulse dynamic compression of the lower extremity enhances flexibility. J Strength Cond Res 28(4): 1058–1064, 2014—This study investigated the effects of peristaltic pulse dynamic compression (PPDC) on range-of-motion (ROM) changes in forward splits. Serious stretching usually involves discomfort and large time investments. Tissue structural changes and stretch tolerance have heretofore been considered the primary mechanisms of enhanced ROM. The PPDC treatment was computer controlled. Circumferential and segmented inflation pressures were induced by feet to hip leggings. Nine subjects, experienced in stretching and a forward split position, volunteered. The subjects were familiarized with the protocol and randomly assigned to an initial condition: experimental (PPDC), or control (CONT). The study involved a crossover design. Second conditions were tested within 1–5 days. All tests were 2 trials of right and left forward splits. Split flexibility was assessed by measuring the height of the anterior superior iliac spine of the rear leg from the floor. Pelvic posture was controlled by rear leg position. The PPDC treatment was 15 minutes of seated PPDC. The control condition was the same except that leggings were not inflated. Pressures of 5 cells in the leggings were set at factory defaults, 70 mm Hg sequentially. Difference score results indicated statistically significant (p ⩽ 0.05) differences by condition and the condition by leg interaction. The rapid acute changes in ROM (PPDC: right 25.3%, left 33.3%; CONT: right 12.2%, left 1.0%) support the premise that changes in ROM were dependent on mechanisms other than tissue structural changes and/or stretch tolerance. PPDC provides a means of rapidly enhancing acute ROM requiring less discomfort and time.

Alternative procedures for the three-minute all-out exercise test.

Abstract Clark, IE, Murray, SR, and Pettitt, RW. Alternative procedures for the three-minute all-out exercise test. J Strength Cond Res 27(8): 2104–2112, 2013—The cycling 3-minute all-out exercise test (3 MT) provides the measures of critical power (CP) and the curvature constant (W′) for the relationship between power and time limit to exhaustion in the severe exercise domain. The original procedures for the 3 MT required a preliminary graded exercise test (GXT) to establish the linear factor and the fixed load for the test. We evaluated a new procedure of establishing the load for the 3 MT using a percentage of body mass (% BM). Fifteen subjects of varied fitness levels completed a custom GXT-verification protocol to establish the gas exchange threshold and V[Combining Dot Above]O2max, a 3 MT using a load derived with the linear factor, and a 3 MT using a % BM. The subjects also completed a subsequent exhaustive bout at 10% above CP. The CP and W′ estimated from either protocol did not differ. The CP estimates were consistent (&agr; = 0.97, SEM = 7.1 W, coefficient of variation = 4%); however, W′ was less reliable, a finding true of any method of measuring W′. The V[Combining Dot Above]O2 evoked during the 3 MT was lower than the values evoked by the exhaustive GXT-verification bouts and the 10% above CP bout after the 3 MT. All individual V[Combining Dot Above]O2 values in the 10% above CP bout were “≥” values measured in the 3 MT. Our findings indicate that several viable procedures for administering the 3 MT are plausible.

A Theoretical Method of Using Heart Rate to Estimate Energy Expenditure during Exercise

The American College of Sports Medicine advocates prescribing aerobic exercise intensities based upon target heart rate (THR); however, it advocates estimating oxygen uptake (V̇O2) using metabolic equations Derivations from metabolic equations presume metabolic responses for a given intensity and volume of exercise is exact for each athlete Conversely HR enables the coach to better estimate intensity and energy expenditure relative to an individual athletes aerobic capacity. To develop estimates of V̇O2 and subsequent energy expenditure during exercise at THR, the coach must have actual or estimated rest and maximal HR and V̇O2 values, respectively. This methodological paper describes step-by-step procedures for calculating energy expenditure during exercise at a given THR. Procedures for estimating rest and maximal HR and V̇O2 values are provided to enable the coach an immediate means of implementing this technique into their practice. Quantification of energy expenditure aids the coach in monitoring individualized training responses and developing nutritional plans with input from a dietician

Navicular stress fractures in identical twin runners: high-risk fractures require structured treatment.

Tarsal navicular fractures require an accurate and timely diagnosis to prevent costly and disabling complications. Diagnosis requires a thorough clinical evaluation that focuses on the patients history, particularly his or her training regimen, and diet—as was the case with these 17-year-old girls. Plain radiography, ultrasound, bone scintigraphy, M RI, and CT help make a definitive diagnosis. Treatment of low-risk fractures involves relative rest and cessation of the precipitating activity. High-risk fractures often require non-weight-bearing immobilization, coupled with therapy, and may require surgery.