Blaine C. Long

Skinfold Thickness at 8 Common Cryotherapy Sites in Various Athletic Populations.

CONTEXT Researchers have observed slower cooling rates in thigh muscle with greater overlying adipose tissue, suggesting that cryotherapy duration should be based on the adipose thickness of the treatment site. Skinfold data do not exist for other common cryotherapy sites, and no one has reported how those skinfolds might vary because of physical activity level or sex. OBJECTIVE To determine the variability in skinfold thickness among common cryotherapy sites relative to sex and activity level (National Collegiate Athletic Association Division I athletes, recreationally active college athletes). DESIGN Descriptive laboratory study. SETTING Field. PATIENTS OR OTHER PARTICIPANTS Three hundred eighty-nine college students participated; 196 Division I athletes (157 men, 39 women) were recruited during preseason physicals, and 193 recreationally active college athletes (108 men, 85 women) were recruited from physical education classes. INTERVENTION(S) Three skinfold measurements to within 1 mm were taken at 8 sites (inferior angle of the scapula, middle deltoid, ulnar groove, midforearm, midthigh, medial collateral ligament, midcalf, and anterior talofibular ligament [ATF]) using Lange skinfold calipers. MAIN OUTCOME MEASURE(S) Skinfold thickness in millimeters. RESULTS We noted interactions among sex, activity level, and skinfold site. Male athletes had smaller skinfold measurements than female athletes at all sites except the ATF, scapula, and ulnar groove (F₇,₂₇₀₂ = 69.85, P < .001). Skinfold measurements were greater for recreationally active athletes than their Division I counterparts at all sites except the ATF, deltoid, and ulnar groove (F₇,₂₇₀₂ = 30.79, P < .001). Thigh skinfold measurements of recreationally active female athletes were the largest, and their ATF skinfolds were the smallest. CONCLUSIONS Skinfold thickness at common cryotherapy treatment sites varied based on level of physical activity and sex. Therefore, clinicians should measure skinfold thickness to determine an appropriate cryotherapy duration.

Cold-Water Immersion for Hyperthermic Humans Wearing American Football Uniforms.

CONTEXT Current treatment recommendations for American football players with exertional heatstroke are to remove clothing and equipment and immerse the body in cold water. It is unknown if wearing a full American football uniform during cold-water immersion (CWI) impairs rectal temperature (Trec) cooling or exacerbates hypothermic afterdrop. OBJECTIVE To determine the time to cool Trec from 39.5°C to 38.0°C while participants wore a full American football uniform or control uniform during CWI and to determine the uniforms effect on Trec recovery postimmersion. DESIGN Crossover study. SETTING Laboratory. PATIENTS OR OTHER PARTICIPANTS A total of 18 hydrated, physically active, unacclimated men (age = 22 ± 3 years, height = 178.8 ± 6.8 cm, mass = 82.3 ± 12.6 kg, body fat = 13% ± 4%, body surface area = 2.0 ± 0.2 m(2)). INTERVENTION(S) Participants wore the control uniform (undergarments, shorts, crew socks, tennis shoes) or full uniform (control plus T-shirt; tennis shoes; jersey; game pants; padding over knees, thighs, and tailbone; helmet; and shoulder pads). They exercised (temperature approximately 40°C, relative humidity approximately 35%) until Trec reached 39.5°C. They removed their T-shirts and shoes and were then immersed in water (approximately 10°C) while wearing each uniform configuration; time to cool Trec to 38.0°C (in minutes) was recorded. We measured Trec (°C) every 5 minutes for 30 minutes after immersion. MAIN OUTCOME MEASURE(S) Time to cool from 39.5°C to 38.0°C and Trec. RESULTS The Trec cooled to 38.0°C in 6.19 ± 2.02 minutes in full uniform and 8.49 ± 4.78 minutes in control uniform (t17 = -2.1, P = .03; effect size = 0.48) corresponding to cooling rates of 0.28°C·min(-1) ± 0.12°C·min(-1) in full uniform and 0.23°C·min(-1) ± 0.11°C·min(-1) in control uniform (t17 = 1.6, P = .07, effect size = 0.44). The Trec postimmersion recovery did not differ between conditions over time (F1,17 = 0.6, P = .59). CONCLUSIONS We speculate that higher skin temperatures before CWI, less shivering, and greater conductive cooling explained the faster cooling in full uniform. Cooling rates were considered ideal when the full uniform was worn during CWI, and wearing the full uniform did not cause a greater postimmersion hypothermic afterdrop. Clinicians may immerse football athletes with hyperthermia wearing a full uniform without concern for negatively affecting body-core cooling.

Validity of Core Temperature Measurements at 3 Rectal Depths During Rest, Exercise, Cold-Water Immersion, and Recovery

CONTEXT   No evidence-based recommendation exists regarding how far clinicians should insert a rectal thermistor to obtain the most valid estimate of core temperature. Knowing the validity of temperatures at different rectal depths has implications for exertional heat-stroke (EHS) management. OBJECTIVE   To determine whether rectal temperature (Trec) taken at 4 cm, 10 cm, or 15 cm from the anal sphincter provides the most valid estimate of core temperature (as determined by esophageal temperature [Teso]) during similar stressors an athlete with EHS may experience. DESIGN   Cross-sectional study. SETTING   Laboratory. PATIENTS OR OTHER PARTICIPANTS   Seventeen individuals (14 men, 3 women: age = 23 ± 2 years, mass = 79.7 ± 12.4 kg, height = 177.8 ± 9.8 cm, body fat = 9.4% ± 4.1%, body surface area = 1.97 ± 0.19 m2). INTERVENTION(S)   Rectal temperatures taken at 4 cm, 10 cm, and 15 cm from the anal sphincter were compared with Teso during a 10-minute rest period; exercise until the participants Teso reached 39.5°C; cold-water immersion (∼10°C) until all temperatures were ≤38°C; and a 30-minute postimmersion recovery period. The Teso and Trec were compared every minute during rest and recovery. Because exercise and cooling times varied, we compared temperatures at 10% intervals of total exercise and cooling durations for these periods. MAIN OUTCOME MEASURE(S)   The Teso and Trec were used to calculate bias (ie, the difference in temperatures between sites). RESULTS   Rectal depth affected bias (F2,24 = 6.8, P = .008). Bias at 4 cm (0.85°C ± 0.78°C) was higher than at 15 cm (0.65°C ± 0.68°C, P < .05) but not higher than at 10 cm (0.75°C ± 0.76°C, P > .05). Bias varied over time (F2,34 = 79.5, P < .001). Bias during rest (0.42°C ± 0.27°C), exercise (0.23°C ± 0.53°C), and recovery (0.65°C ± 0.35°C) was less than during cooling (1.72°C ± 0.65°C, P < .05). Bias during exercise was less than during postimmersion recovery (0.65°C ± 0.35°C, P < .05). CONCLUSIONS   When EHS is suspected, clinicians should insert the flexible rectal thermistor to 15 cm (6 in) because it is the most valid depth. The low level of bias during exercise suggests Trec is valid for diagnosing hyperthermia. Rectal temperature is a better indicator of pelvic organ temperature during cold-water immersion than is Teso.

Ankle Joint Angle and Lower Leg Musculotendinous Unit Responses to Cryotherapy.

Abstract Akehi, K, Long, BC, Warren, AJ, and Goad, CL. Ankle joint angle and lower leg musculotendinous unit responses to cryotherapy. J Strength Cond Res 30(9): 2482–2492, 2016—The use of cold application has been debated for its influence on joint range of motion (ROM) and stiffness. The purpose of this study was to determine whether a 30-minute ice bag application to the plantarflexor muscles or ankle influences passive ankle dorsiflexion ROM and lower leg musculotendinous stiffness (MTS). Thirty-five recreationally active college-aged individuals with no history of lower leg injury 6 months before data collection volunteered. On each testing day, we measured maximum passive ankle dorsiflexion ROM (°) and plantarflexor torque (N·m) on an isokinetic dynamometer to calculate the passive plantarflexor MTS (N·m per degree) at 4 joint angles before, during, and after a treatment. Surface electromyography amplitudes (&mgr;V), and skin surface and ambient air temperature (°C) were also measured. Subjects received an ice bag to the posterior lower leg, ankle joint, or nothing for 30 minutes in different days. Ice bag application to the lower leg and ankle did not influence passive ROM (F (12,396) = 0.67, p = 0.78). Passive torque increased after ice bag application to the lower leg (F (12,396) = 2.21, p = 0.011). Passive MTS at the initial joint angle increased after ice bag application to the lower leg (F (12,396) = 2.14, p = 0.014) but not at the other joint angles (p > 0.05). Surface electromyography amplitudes for gastrocnemius and soleus muscles increased after ice application to the lower leg (F (2,66) = 5.61, p = 0.006; F (12,396) = 3.60, p < 0.001). Ice bag application to the lower leg and ankle joint does not alter passive dorsiflexion ROM but increases passive ankle plantarflexor torque in addition to passive ankle plantarflexor MTS at the initial joint angle.

Application of Menthol Counterirritant: Effect on Hamstring Flexibility, Sensation of Pressure, and Skin Surface Temperature

Topical analgesics, or counterirritants, are recommended to numb the skin and decrease tissue temperature. This study examined a topical analgesic with menthol, combined with static stretching on hip fl exion range of motion (ROM), sensation of pressure, and skin surface temperature. Thirty individuals with � 90° of passive hip fl exion ROM participated. Participants experienced 1 of 3 treatments (Flexall 454, placebo [massage lotion with peppermint oil], and control), according to a balanced Latin square, on 3 days separated by 48 hours. Hip fl exion ROM increased over time (F 1,21 = 104.03; P = .001). However, there was no diff erence in ROM between treatment (P = .92) or day (P = .93). Sensation of pressure remained the same among treatment (P = .75), day (P = .93), and time (P = .93). Temperature did not change for treatment (P = .58), day (P = .86), or time (P = .59). It does not appear that a topical analgesic with menthol infl uences hip fl exion ROM, sensation of pressure, or skin surface temperature. [Athletic Training & Sports Health Care. 2013:5(x):xxx-xxx.]

Prophylactic stretching does not reduce cramp susceptibility

Introduction: Some clinicians advocate stretching to prevent muscle cramps. It is unknown whether static or proprioceptive neuromuscular facilitation (PNF) stretching increases cramp threshold frequency (TFc), a quantitative measure of cramp susceptibility. Methods: Fifteen individuals completed this randomized, counterbalanced, cross‐over study. We measured passive hallux range of motion (ROM) and then performed 3 minutes of either static stretching, PNF stretching (hold–relax—with agonist contraction), or no stretching. ROM was reassessed and TFc was measured. Results: PNF stretching increased hallux extension (pre‐PNF 81 ± 11°, post‐PNF 90 ± 10°; P < 0.05) but not hallux flexion (pre‐PNF 40 ± 7°, post‐PNF 40 ± 7°; P > 0.05). Static stretching increased hallux extension (pre‐static 80 ± 11°, post‐static 88 ± 9°; P < 0.05) but not hallux flexion (pre‐static 38 ± 9°, post‐static 39 ± 8°; P > 0.05). No ROM changes occurred with no stretching (P > 0.05). TFc was unaffected by stretching (no stretching 18 ± 7 Hz, PNF 16 ± 4 Hz, static 16 ± 5 Hz; P = 0.37). Discussion: Static and PNF stretching increased hallux extension, but neither increased TFc. Acute stretching may not prevent muscle cramping. Muscle Nerve 57: 473–477, 2018

Muscle Cramp Susceptibility Increases Following a Volitionally‐Induced Muscle Cramp

Muscle cramping may increase peripheral nervous system excitability. It is unknown if, and how long, cramp susceptibility is affected by previous cramping. We tested whether volitionally induced muscle cramps (VIMCs) lowered cramp threshold frequency (TFc) and how long TFc was affected post‐VIMC.

Temperate-Water Immersion as a Treatment for Hyperthermic Humans Wearing American Football Uniforms

CONTEXT   Cold-water immersion (CWI; 10°C) can effectively reduce body core temperature even if a hyperthermic human is wearing a full American football uniform (PADS) during treatment. Temperate-water immersion (TWI; 21°C) may be an effective alternative to CWI if resources for the latter (eg, ice) are unavailable. OBJECTIVE   To measure rectal temperature (Trec) cooling rates, thermal sensation, and Environmental Symptoms Questionnaire (ESQ) scores of participants wearing PADS or shorts, undergarments, and socks (NOpads) before, during, and after TWI. DESIGN   Crossover study. SETTING   Laboratory. PATIENTS OR OTHER PARTICIPANTS   Thirteen physically active, unacclimatized men (age = 22 ± 2 years, height = 182.3 ± 5.2 cm, mass = 82.5 ± 13.4 kg, body fat = 10% ± 4%, body surface area = 2.04 ± 0.16 m2). INTERVENTION(S)   Participants exercised in the heat (40°C, 50% relative humidity) on 2 days while wearing PADS until Trec reached 39.5°C. Participants then underwent TWI while wearing either NOpads or PADS until Trec reached 38°C. Thermal sensation and ESQ responses were collected at various times before and after exercise. MAIN OUTCOME MEASURE(S)   Temperate-water immersion duration (minutes), Trec cooling rates (°C/min), thermal sensation, and ESQ scores. RESULTS   Participants had similar exercise times (NOpads = 38.1 ± 8.1 minutes, PADS = 38.1 ± 8.5 minutes), hypohydration levels (NOpads = 1.1% ± 0.2%, PADS = 1.2% ± 0.2%), and thermal sensation ratings (NOpads = 7.1 ± 0.4, PADS = 7.3 ± 0.4) before TWI. Rectal temperature cooling rates were similar between conditions (NOpads = 0.12°C/min ± 0.05°C/min, PADS = 0.13°C/min ± 0.05°C/min; t12 = 0.82, P = .79). Thermal sensation and ESQ scores were unremarkable between conditions over time. CONCLUSIONS   Temperate-water immersion produced acceptable (ie, >0.08°C/min), though not ideal, cooling rates regardless of whether PADS or NOpads were worn. If a football uniform is difficult to remove or the patient is noncompliant, clinicians should begin water-immersion treatment with the athlete fully equipped. Clinicians should strive to use CWI to treat severe hyperthermia, but when CWI is not feasible, TWI should be the next treatment option because its cooling rate was higher than the rates of other common modalities (eg, ice packs, fanning).