Robert W. Pettitt

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.

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.

Evaluation of circuit-training intensity for firefighters.

Abel, MG, Mortara, AJ, and Pettitt, RW. Evaluation of circuit-training intensity for firefighters. J Strength Cond Res 25(10): 2895–2901, 2011—Firefighters are required to perform a variety of strenuous occupational tasks that require high levels of both aerobic and anaerobic fitness. Thus, it is critical that firefighters train at an appropriate intensity to develop adequate levels of aerobic and anaerobic fitness. Circuit training is a unique training method that stresses both energy systems and therefore may be a viable training method to enhance firefighter preparedness. Thus, the purpose of this study was to compare the aerobic and anaerobic intensities of a circuit-based workout to physiological data previously reported on firefighters performing fire suppression and rescue tasks. Twenty career firefighters performed a workout that included 2 rotations of 12 exercises that stressed all major muscle groups. Heart rate was recorded at the completion of each exercise. Blood lactate was measured before and approximately 5 minutes after the workout. The workout heart rate and post–workout blood lactate responses were statistically compared to data reported on firefighters performing fire suppression and rescue tasks. The mean circuit-training heart rate was similar to previously reported heart rate responses from firefighters performing simulated smoke-diving tasks (79 ± 5 vs. 79 ± 6% maximum heart rate [HRmax], p = 0.741), but lower than previously reported heart rate responses from firefighters performing fire suppression tasks (79 ± 5 vs. 88 ± 6% HRmax, p < 0.001). The workout produced a similar peak blood lactate compared to that when performing firefighting tasks (12 ± 3 vs. 13 ± 3 mmol·L−1, p = 0.084). In general, the circuit-based workout produced a lower cardiovascular stress but a similar anaerobic stress as compared to performing firefighting tasks. Therefore, firefighters should supplement low-intensity circuit-training programs with high-intensity cardiovascular and resistance training (e.g., ≥85% 1-repetition maximum) exercises to adequately prepare for the variable physical demands of firefighting.

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

The standard difference score: a new statistic for evaluating strength and conditioning programs.

Inferential statistics help the strength and conditioning specialist to determine if a team is responding to a strength and conditioning program overall; however, such statistics do not detect unusual responses among individuals such as those who may be overtraining. This article introduces the standard difference score (SDS), a new statistic for evaluating strength and conditioning programs. The SDSs are standard scores (z score) derived from a change in a raw strength and conditioning performance score. They are simple to calculate and sort, easy to plot, and can be aggregated to detect athletes exhibiting extreme performance changes from a battery of tests. Standard difference scores, when evaluated with skewness, can be substituted for conventional exploratory statistics generated with higher end statistical software programs.

Influence of Load Carriage on High-Intensity Running Performance Estimation.

Abstract Solomonson, AA, Dicks, ND, Kerr, WJ, and Pettitt, RW. Influence of load carriage on high-intensity running performance estimation. J Strength Cond Res 30(5): 1391–1396, 2016—Load carriage is a necessary burden for tactical athletes. A combination of training modes, including aerobic conditioning and progressive load carriage, may lead to improved performance. The critical speed (CS) concept enables the practitioner to prescribe high-intensity interval training (HIIT) time limits (TLIMs) from a single 3-minute all-out exercise test (3 MT). We sought to examine the effect of a standard load carriage (18.86 kg) on CS and the finite running capacity > CS (D′). A group of trained subjects (age: 26 ± 5 years, height: 181 ± 4 cm, body mass [BM]: 90 ± 14 kg) completed a loaded and unloaded (UL) 3 MT. The CS was reduced by 0.66 ± 0.24 m·s−1 (p < 0.01) in the loaded condition. There was a small nonsignificant increase in D′ (21.25 ± 39.53 m, p = 0.07). The higher the % load carriage relative to BM is, the greater decline in CS (r = 0.83, p < 0.01). A revised CS with load carriage from the UL 3 MT may be calculated using: adjusted CS = original CS + ([−0.0638 × %load]) + 0.6982. Our results indicate that revised CS and TLIMs for fixed distance, fixed time, or fixed speed HIIT prescriptions may be derived from a UL 3 MT. Such calculations would enable more expeditious training for tactical athletes. We recommend further research involving implementation of HIIT using this new method.