Christopher D. Stickley

Isokinetic Peak Torque Ratios and Shoulder Injury History in Adolescent Female Volleyball Athletes

CONTEXT Few researchers have examined shoulder strength in adolescent volleyball athletes despite increasing levels of participation in this age group. OBJECTIVE To compare medial and lateral isokinetic peak torque of the rotator cuff among skill levels and between athletes with and without a history of shoulder injury. DESIGN Cross-sectional design. SETTING The Human Performance Lab and Athletic Training Lab. PATIENTS OR OTHER PARTICIPANTS Thirty-eight female adolescent club volleyball athletes from 10 to 15 years of age (mean = 13.02 +/- 1.60 years). MAIN OUTCOME MEASURE(S) We measured concentric and eccentric peak torque of the medial and lateral rotators of the shoulder and calculated resultant cocking and spiking ratios based on peak torque values. RESULTS Athletes at higher skill levels had higher peak torque measurements in concentric and eccentric medial and lateral rotation compared with the athletes at lower skill levels. No differences in peak torque existed between participants with or without an injury history 6 months before the study. Strength ratios did not differ across skill levels, but previously injured participants produced lower eccentric medial rotation to concentric lateral rotation ratios compared with participants without a history of injury (P = .02). At the highest skill level, previously injured participants produced lower eccentric lateral rotation to concentric medial rotation ratios compared with participants without an injury history (P = .04). CONCLUSIONS Differences in medial and lateral shoulder rotator strength ratios appear to be related more to injury prevalence than to absolute strength. Shoulder dysfunction related to strength ratio deficits also may exist in adolescent female volleyball athletes. Preventive shoulder strengthening programs focused on improving eccentric strength and correcting imbalances between medial and lateral rotators may be warranted for all female adolescent volleyball athletes.

Reliability and accuracy of handheld stopwatches compared with electronic timing in measuring sprint performance.

Hetzler, RK, Stickley, CD, Lundquist, KM, and Kimura, IF. Reliability and accuracy of handheld stopwatches compared with electronic timing in measuring sprint performance. J Strength Cond Res 22(6): 1969-1976, 2008-This study assessed reliability of split times obtained by handheld stopwatches (HHSs) compared with electronic timing (ET) during a 200-m sprint. Two HHS timing methods were compared with ET: single-split timers (SST) and multiple-split timers (MST). Twenty-six timers without previous experience were given instruction and completed practice trials until good agreement was achieved between ET and HHS. Trained runners (8 males, 10 females) were timed for each 25-m interval on a standard 200-m course. Repeated-measures analysis of variance and intraclass correlation models were used to determine reliability. A total of 248 split times were analyzed. No significant differences were found between the three timing methods (p > 0.99), and calculated intraclass correlation values were high (0.988). Mean error between SST, MST, and ET (−0.04 ± 0.24 and −0.05 ± 0.24 seconds, respectively) indicated faster HHS times, though not significantly. However, absolute errors were considerably larger (0.15 ± 0.20 and 0.16 ± 0.19 between SST, MST, and ET, respectively). The HHS-recorded splits were faster than ET in 67.3% of splits and slower in 29.4%. The distribution of errors made the development of a reliable correction factor to convert HHS to ET impossible. It was concluded that on the basis of the small mean error and high intraclass correlations, the use of HHSs may be a viable alternative to ET in collecting group data. However, on the basis of the absolute error between HHS and ET, when high degrees of precision are required, ET should be used, and reliable correction of HHS to ET values is not possible. It was further concluded that HHS times should be reported without attempting correction and interpreted in light of the shortcomings of the HHS method.

Crural Fascia and Muscle Origins Related to Medial Tibial Stress Syndrome Symptom Location

PURPOSE Traction-induced injury, related to muscles of the superficial and deep posterior compartments, has been implicated as the cause of medial tibial stress syndrome (MTSS) with symptoms commonly occurring in the distal third of the posteromedial tibia. Standard anatomic texts do not identify this region as an attachment site for these structures. Research into the anatomical arrangement of these structures has been inconclusive. The deep crural fascia (DCF) has been implicated as a cause of traction-induced injury in MTSS but not fully researched. The purpose of this study was to define the tibial origins of the DCF and the muscles of the superficial and deep posterior compartments relative to MTSS-related pain commonly reported along the distal one half to one third of the diaphysis of the medial tibial border and to identify the prevalence of a soleal aponeurosis. METHODS The tibial attachments of the DCF, the soleus, the flexor digitorum longus, and the tibialis posterior were quantified relative to the medial malleolus in sixteen cadaver specimens. RESULTS Mean distal attachments to the medial tibial border were superior to the distal third of the tibia for the muscles of the posterior compartments, suggesting that the role of the soleus, the tibialis posterior, and the flexor digitorum longus in producing pain typically associated with MTSS may be limited. The DCF of all but three specimens attached along the entire length of the medial tibia investing the medial malleolus. CONCLUSION Traction-induced injury theories involving the muscles of the superficial and deep posterior compartments are not supported by anatomical evidence in the present study. The tibial attachments of the DCF in this study support theories implicating DCF involvement in creating traction-induced injury.

Comparisons of Age-Predicted Maximum Heart Rate Equations in College-Aged Subjects

Cleary, MA, Hetzler, RK, Wages, JJ, Lentz, MA, Stickley, CD, and Kimura, IF. Comparisons of age-predicted maximum heart rate equations in college-aged subjects. J Strength Cond Res 25(9): 2591-2597, 2011—This study investigated the accuracy of age-predicted equations to predict heart rate maximum (HRmax) in a college-age sample and establish efficacy of short-duration anaerobic capacity tests to determine the actual HRmax. A criterion HRmax (CHRmax) was obtained from 96 (52 men and 44 women, age = 22.0 ± 2.8 years, height = 163.9 ± 9.5 cm, 70.6 ± 14.7 kg, resting HR = 68.9 ± 11.2 b·min−1) healthy volunteers during 2 200-m sprint trials on a standard track. Maximal effort was confirmed via plasma lactate ≥7 mmol·L−1 and rating of perceived exertion ≥17 points. The CHRmax was compared to 7 age-predicted HRmax equations: Fox et al., 3 equations from Gellish et al., Tanaka et al., and gender-specific equations from Fairbarn et al., and Hossack et al. Descriptive statistics and standard errors of estimate (SEEs) were calculated. One-way analysis of variance was used to assess differences between the criterion HRmax and the age-predicted HRmax from the 7 equations. The predicted HRmax from the Fox equation and those of Gellish3, Tanaka, and Hossack were all significantly higher (p ≤ 0.05) than the CHRmax. The Fox equation resulted in overpredicting HRmax in 88.5% of the cases compared to the CHRmax. Compared to the CHRmax, the age-predicted HRmax equations resulted in the following percentages of the CHRmax: Fox = 104.8%, SEE = 12.7; Gellish1 = 95.2%, SEE = 12.2; Gellish2 = 99.6%, SEE = 8.3; Gellish3 = 101.8%, SEE = 9.1; Tanaka = 102.0%, SEE = 9.3; Fairbarn = 100.1%, SEE = 8.5; and Hossack = 105.2%, SEE = 13.9 of CHRmax. It was concluded that the Gellish2 and Fairbarn equations were the most accurate of the age-predicted HRmax equations in a college-age population. In practical application, 2 200-m sprint trials provide a reasonable estimate of HRmax compared to a graded exercise test.

Hydration Behaviors Before and After an Educational and Prescribed Hydration Intervention in Adolescent Athletes

CONTEXT The effectiveness of education in modifying hydration behaviors in adolescent athletes is unclear. OBJECTIVE To assess the hydration status and behaviors of female athletes before and after a 1-time educational intervention and prescribed hydration intervention in a warm, humid, tropical environment. DESIGN Cohort study. SETTING Non-air-conditioned gymnasium in a tropical environment (indoor wet bulb globe temperature = 24.0 ± 0.2°C). Patient or Other Participants: Thirty-six female adolescent elite volleyball players (age = 14.8 ± 0.8 years, height = 168.2 ± 8.2 cm, mass = 60.8 ± 9.0 kg, body mass index = 21.7 ± 2.7, body surface area = 1.65 ± 0.14 m(2), body surface area to mass ratio = 2.71 ± 0.18 m(2)·kg(-1)·10(-2)) participated. INTERVENTION(S) Four observational periods consisting of 3 practices per observational period separated by 48 hours. The 4 periods included a control period, educational intervention, prescribed hydration intervention (PHI), and observational follow-up (OF-U). After the control period, an educational intervention consisting of a slide presentation was provided to the participants, followed by a week of observation. In the PHI, a precalculated volume of water based on individual sweat rate was consumed every 20 minutes during each 2-hour practice. During all other periods, participants consumed their fluid of choice ad libitum. The order of the treatment periods was not randomized and was the same for all participants. MAIN OUTCOME MEASURE(S) Prepractice to postpractice changes in body mass (ΔBM), percentage of body mass lost (%BML), urine specific gravity, urine color, urine osmolality, sweat rate, and volume of fluid consumed (F(vol)). RESULTS The PHI was the only period during which participants maintained body mass (ΔBM = 0.05 ± 1.3%); F(vol) consumed was greatest during this time (F(vol) = 1.3 ± 0.4 L; F(1,3) = 34.869, P ≤ .001). TheΔBM was less for the PHI (ΔBM = 0.05 ± 0.9 kg, %BML = 0.04 ± 1.3%) than the OF-U period (ΔBM = -0.7 ± 1.1 kg, %BML = -1.2 ± 1.9%; F(1,3) = 6.220, P = .01). The F(vol) (1.3 ± 0.4 L) and percentage of fluid consumed (143.7 ± 110.8%) to restore sweat loss for the PHI period were higher than for any other period (F(1,3) = 34.869, P ≤ .001). None of the participants experienced serious dehydration in any of the conditions. CONCLUSIONS A 1-time education session alone was not successful in changing hydration behaviors. However, prescribing individualized hydration protocols improved hydration for adolescents exercising in a warm, humid environment.

Prediction of anaerobic power values from an abbreviated WAnT protocol.

The traditional 30-second Wingate anaerobic test (WAnT) is a widely used anaerobic power assessment protocol. An abbreviated protocol has been shown to decrease the mild to severe physical discomfort often associated with the WAnT. Therefore, the purpose of this study was to determine whether a 20-second WAnT protocol could be used to accurately predict power values of a standard 30-second WAnT. In 96 college females, anaerobic power variables were assessed using a standard 30-second WAnT protocol. Maximum power values as well as instantaneous power at 10, 15, and 20 seconds were recorded. Based on these results, stepwise regression analysis was performed to determine the accuracy with which mean power, minimum power, 30-second power, and percentage of fatigue for a standard 30-second WAnT could be predicted from values obtained during the first 20 seconds of testing. Mean power values showed the highest level of predictability (R2 = 0.99) from the 20-second values. Minimum power, 30-second power, and percentage of fatigue also showed high levels of predictability (R2 = 0.91, 0.84, and 0.84, respectively) using only values obtained during the first 20 seconds of the protocol. An abbreviated (20-second) WAnT protocol appears to effectively predict results of a standard 30-second WAnT in college-age females, allowing for comparison of data to published norms. A shortened test may allow for a decrease in unwanted side effects associated with the traditional WAnT protocol.

The Effect of Dynamic Intermittent Hypoxic Conditioning on Arterial Oxygen Saturation

Abstract Background.—Increases in arterial oxygen saturation (SaO2) in response to intermittent hypoxic exposure (IHE) are well established. However, IHE protocols have historically involved static hypoxic environments. The effect of a dynamic hypoxic environment on SaO2 is not known. Objective.—The purpose of this study was to examine the effect of dynamic IHE conditioning on SaO2 using the Cyclical Variable Altitude Conditioning Unit. Methods.—Thirteen trained participants (9 males, age 30.1 ± 9.2 years; 4 females, age 30.3 ± 8.9 years) residing at or near sea level were exposed to a 7-week IHE conditioning protocol (mean total exposure time = 30.8 hours). Participants were exposed to a constantly varying series of hypobaric pressures simulating altitudes from sea level to 6858 m (22 500 feet) in progressive conditioning tiers, creating a dynamic hypoxic environment. SaO2 was evaluated using pulse oximetry (SpO2) 4 times: at 2740, 3360, and 4570 m, prior to and following the first 3 weeks of IHE, and at 4570, 5490, and 6400 m at the start and end of the final 4 weeks. Results.—SpO2 improved 3.5%, 3.8%, and 4.1% at 2470, 3360, and 4570 m, respectively (P < .05), and 3.3%, 3.4%, and 5.9% at 4570, 5490, and 6400 m, respectively (P < .05). At 4570 m, SpO2 increased from 81.7% ± 6.5% to 89.1% ± 3.2% over the entire 7-week conditioning period. Discussion.—The dynamic intermittent hypoxic conditioning protocol used in the present study resulted in an acclimation response, such that SpO2 was significantly increased at all altitudes tested, with shorter exposure times than generally reported.

Effects of combination oral contraceptives on strength development in women athletes.

Nichols, AW, Hetzler, RK, Villanueva, RJ, Stickley, CD, and Kimura, IF. Effects of combination oral contraceptives on strength development in women athletes. J Strength Cond Res 22(5): 1625-1632, 2008-This study was designed to investigate the effects of combination oral contraceptive agents (OCAs) on strength and torque production in collegiate women softball and water polo athletes who participated in a 12-week strength development program. A double-blind research design was used to mask subjects to the main outcome of interest. Thirty-one women collegiate softball and water polo players were divided into experimental (OCA users, n = 13), and control (non-OCA users, n = 18) groups. All subjects participated in the same supervised 12-week preseason strength development program. One-repetition maximum bench press (1RMBP), 10-repetition maximum leg extension (10RMLE), isokinetic peak torque bench press (IKBP), and isokinetic peak torque leg extension (IKLE) data were collected at weeks 0 (pre-test), 4, 8, and 12 (post-test). Significant increases in strength and torque production over time were identified regardless of group for 1RMBP, 10RMLE, and IKLE. No significant differences in IKBP torque production occurred during the 12-week strength training program. No significant differences in 1RMBP, 10RMLE, IKBP, or IKLE occurred between the OCA users and the non-OCA users groups. It was concluded that, within the limitations of the study, the use of combination OCAs did not provide sufficient androgenic effect to increase strength gains beyond the stimulus of the training protocol.

Allometric Scaling of Wingate Anaerobic Power Test Scores in Women

In this study, we developed allometric exponents for scaling Wingate anaerobic test (WAnT) power data that are effective in controlling for body mass (BM) and lean body mass (LBM) and established a normative WAnT data set for college-age women. One hundred women completed a standard WAnT. Allometric exponents and percentile ranks for peak (PP) and mean power (MP) were established. Allometric exponents were applied to WAnT scores for an independent sample (n = 31) to assess external validity. PP and MP were 477.0 W (SD = 80.0) and 372.6 W (SD = 61.5), respectively. Allometric exponents for PP and MP scaled for BM were b = 0.92 and b = 0.76, respectively, and for LBM they were b = 0.93 and b = 0.91, respectively. In the independent sample, these exponents produced correlations between allometrically scaled PP and MP and BM of r =-.02 and r = .02, respectively. Correlations between allometrically scaled PP and MP and LBM were r = .004 and r = -.02, respectively. The allometric exponents were effective in partialing out the effect of BM for PP and MP and demonstrated acceptable levels of external validity when applied to an independent sample. The allometric exponents and normative values provide a useful tool for comparing WAnT scores in college-age women without the confounding effects of BM or LBM.

Asymmetry Between Lower Limbs During Rested and Fatigued State Running Gait in Healthy Individuals

Although normal gait is often considered symmetrical in healthy populations, differences between limbs during walking suggest that limbs may be used preferentially for braking or propulsion. The purpose of this study was to evaluate kinematic and kinetic variables, at both rested state and following a two-stage treadmill fatiguing run, for asymmetry between limbs. Kinematic (240Hz) and kinetic (960Hz) running data were collected bilaterally for 20 physically active individuals at both rested and fatigued states. Symmetry angles were calculated to quantify asymmetry magnitude at rested and fatigued states. Paired t-tests were used to evaluate differences between right and left limbs at rested and fatigued states, as well as rested and fatigued states symmetry angles. Variables that have been previously associated with the development of overuse injuries, such as knee internal rotation, knee stiffness, loading rate, and adduction free moment, were found to be significantly different between limbs at both rested and fatigued states. Significant differences in vertical stiffness were found, potentially indicating functional asymmetry during running. Symmetry angle was used to investigate changes in percentage of asymmetry at rested and fatigued states. Small (1-6%), but significant decreases in vertical stiffness, loading rate, and free moment symmetry angles indicate that these variables may become more symmetrical with fatigue. Knee internal rotation and knee stiffness became more asymmetrical with fatigue, increasing by 14% and 5.3%, respectively. The findings of the current study indicate that fatigue induced changes in gait may progress knee movement pattern asymmetry.