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.

INTRODUCTION: 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. METHODS: Fifteen cramp-prone participants volitionally induced a flexor hallucis brevis (FHB) cramp on 4 separate days. FHB TFc was measured before VIMC (i.e., baseline) and 5, 30, and 60 min post-VIMC. VIMC electromyography (EMG) amplitude, VIMC duration, and perceived VIMC intensity were measured to ensure consistency of VIMC between days. RESULTS: VIMC EMG amplitude, duration, and perceived intensity were similar between days (P > 0.05). VIMC lowered TFc ; baseline TFc (18 ± 6 Hz) was higher than 5-min (14 ± 6 Hz), 30-min (14 ± 5 Hz), and 60-min TFc (14 ± 5 Hz; P < 0.05). DISCUSSION: Acute VIMCs increase cramp susceptibility. Clinicians should apply treatments for at least 60 min postcramp to decrease the probability of cramp recurrence. Muscle Nerve 56: E95-E99, 2017.

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

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 (µV), 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.

Effect of foam rolling and static stretching on passive hip-flexion range of motion.

CONTEXT: Many athletes report that foam rollers help release tension in their muscles, thus resulting in greater range of motion (ROM) when used before stretching. To date, no investigators have examined foam rollers and static stretching. OBJECTIVE: To determine if foam rolling before static stretching produces a significant change in passive hip-flexion ROM. DESIGN: Controlled laboratory study. SETTING: Research laboratory. PARTICIPANTS: 40 subjects with less than 90° of passive hip-flexion ROM and no lower-extremity injury in the 6 mo before data collection. INTERVENTIONS: During each of 6 sessions, subjects' passive hip-flexion ROM was measured before and immediately after static stretching, foam rolling and static stretching, foam rolling, or nothing (control). To minimize accessory movement of the hip and contralateral leg, subjects lay supine with a strap placed across their hip and another strap located over the uninvolved leg just superior to the patella. A bubble inclinometer was then aligned on the thigh of the involved leg, with which subjects then performed hip flexion. MAIN OUTCOME MEASURE: Change in passive hip-flexion ROM from the preintervention measure on day 1 to the postintervention measure on day 6. RESULTS: There was a significant change in passive hip-flexion ROM regardless of treatment (F3,17 = 8.06, P = .001). Subjects receiving foam roll and static stretch had a greater change in passive hip-flexion ROM compared with the static-stretch (P = .04), foam-rolling (P = .006), and control (P = .001) groups. CONCLUSIONS: Our results support the use of a foam roller in combination with a static-stretching protocol. If time allows and maximal gains in hip-flexion ROM are desired, foam rolling the hamstrings muscle group before static stretching would be appropriate in noninjured subjects who have less than 90° of hamstring ROM.

Production of consistent pain by intermittent infusion of sterile 5% hypertonic saline, followed by decrease of pain with cryotherapy.

CONTEXT: It is suggested that postinjury pain is difficult to examine; thus, investigators have developed experimental pain models. To minimize pain, cryotherapy (cryo) is applied, but reports on its effectiveness are limited. OBJECTIVE: To investigate a pain model for the anterior knee and examine cryo in reducing the pain. DESIGN: Controlled laboratory study. SETTING: Therapeutic modality laboratory. PARTICIPANTS: 30 physically active healthy male subjects who were free from any lower extremity orthopedic, neurological, cardiovascular, or endocrine pathologies. MAIN OUTCOME MEASURES: Perceived pain was measured every minute. Surface temperature was also assessed in the center of the patella and the popliteal fossa. RESULTS: There was a significant interaction between group and time (F68,864 = 3.0, P = .0001). At the first minute, there was no difference in pain between the 3 groups (saline/cryo = 4.80 ± 4.87 mm, saline/sham = 2.80 ± 3.55 mm, no saline/cryo = 4.00 ± 3.33 mm). During the first 5 min, pain increased from 4.80 ± 4.87 to 45.90 ± 21.17 mm in the saline/cryo group and from 2.80 ± 3.55 to 31.10 ± 20.25 mm in the saline/sham group. Pain did not change within the no-saline/cryo group, 4.00 ± 3.33 to 1.70 ± 1.70 mm. Pain for the saline/sham group remained constant for 17 min. Cryo decreased pain for 16 min in the saline/cryo group. There was no difference in preapplication surface temperature between or within each group. No change in temperature occurred within the saline/sham. Cooling and rewarming were similar in both cryo groups. Ambient temperature fluctuated less than 1°C during data collection. CONCLUSION: Intermittent infusion of sterile 5% hypertonic saline may be a useful experimental pain model in establishing a constant level of pain in a controlled laboratory setting. Cryotherapy decreased the induced anterior knee pain for 16 min.

The influence of ratio and allometric scaling procedures for normalizing upper body power output in division I collegiate football players.

The purpose of the present study was to examine the differences in upper body power output among lineman and nonlineman division I collegiate football players and to examine the influence of 2 normalization procedures: (a) simple ratio scaling and (b) standardized allometric scaling. Ten lineman (mean +/- SD: age = 19.3 +/- 1.6 years; height = 187.7 +/- 4.7 cm; mass = 127.7 +/- 13.3 kg) and 14 nonlineman (19.6 +/- 1.4 years; 181.8 +/- 5.2 cm; 92.3 +/- 10.6 kg) performed a multiple repetition bench press power test at 50% of their 1 repetition maximum. Peak power (PP) was determined from a Tendo weightlifting analyzer that was attached to the barbell. The PP values were then analyzed under 3 conditions that included: (a) no scaling (absolute values), (b) ratio scaling (PP body mass), and (c) allometric scaling (PP body mass). The results indicated that the larger lineman demonstrated greater absolute PP values (p = 0.02); however, ratio scaling favored the smaller nonlineman group (p = 0.04). There were no differences in PP values between positions after the standardized allometric scaling procedure (p = 0.60). These findings indicated that the standardized allometric scaling procedure may be a more effective method for normalizing PP values among elite division I collegiate football players.

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 participant's 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.

Exercise and quadriceps muscle cooling time.

CONTEXT: Cryotherapy is commonly used for a variety of purposes; however, the body's response to cryotherapy immediately postexercise is unknown. OBJECTIVE: To investigate the effect of prior exercise on crushed-ice-bag treatment of a large muscle group. DESIGN: 2 x 3 repeated-measures design on depth (1 cm and 2 cm below adipose tissue) and treatment (exercise followed by ice, exercise followed by no ice, and no exercise followed by ice). SETTING: Sports Injury Research Laboratory. PATIENTS OR OTHER PARTICIPANTS: Six physically active, uninjured male volunteers. INTERVENTION(S): For the 2 exercise conditions, subjects rode a stationary cycle ergometer at 70% to 80% of their age-predicted maximum heart rate, as calculated by the Karvonen method. For the no-exercise condition, subjects lay supine on a treatment table. The cryotherapy treatment consisted of a 1-kg ice bag applied to the anterior mid thigh. For the no-ice condition, subjects lay supine on a treatment table. MAIN OUTCOME MEASURE(S): Time required for the intramuscular temperatures at the 1-cm and 2-cm depths below adipose tissue to return to pre-exercise baseline and time required to cool the 1-cm and 2-cm depths to 10 degrees C below the pre-exercise temperature. RESULTS: The time to cool the rectus femoris to the pre-exercise temperature using a crushed-ice-bag treatment was reduced by approximately 40 minutes (P < .001). The ice bag cooled the 1-cm and 2-cm depths to the pre-exercise temperature within 7 minutes (P = .38), but the 2-cm tissue depth took nearly 13.5 minutes longer to cool than the 1-cm depth when no ice was applied (P = .001). The 1-cm depth cooled to 10 degrees C below the pre-exercise temperature about 8 minutes sooner than the 2-cm depth, regardless of whether the tissue was exercised or not (P < .001). Exercise shortened the cooling time to 10 degrees C below the pre-exercise temperature by approximately 13 minutes (P = .05). CONCLUSIONS: Exercise before cooling with a crushed-ice bag enhanced the removal of intramuscular heat.

Necessity of Removing American Football Uniforms From Humans With Hyperthermia Before Cold-Water Immersion.

CONTEXT: The National Athletic Trainers' Association and the American College of Sports Medicine have recommended removing American football uniforms from athletes with exertional heat stroke before cold-water immersion (CWI) based on the assumption that the uniform impedes rectal temperature (T(rec)) cooling. Few experimental data exist to verify or disprove this assumption and the recommendations. OBJECTIVES: To compare CWI durations, T(rec) cooling rates, thermal sensation, intensity of environmental symptoms, and onset of shivering when hyperthermic participants wore football uniforms during CWI or removed the uniforms immediately before CWI. DESIGN: Crossover study. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: Eighteen hydrated, physically active men (age = 22 ± 2 years, height = 182.5 ± 6.1 cm, mass = 85.4 ± 13.4 kg, body fat = 11% ± 5%, body surface area = 2.1 ± 0.2 m(2)) volunteered. INTERVENTION(S): On 2 days, participants exercised in the heat (approximately 40°C, approximately 40% relative humidity) while wearing a full American football uniform (shoes; crew socks; undergarments; shorts; game pants; undershirt; shoulder pads; jersey; helmet; and padding over the thighs, knees, hips, and tailbone [PADS]) until T(rec) reached 39.5°C. Next, participants immersed themselves in water that was approximately 10°C while wearing either undergarments, shorts, and crew socks (NOpads) or PADS without shoes until Trec reached 38°C. MAIN OUTCOME MEASURE(S): The CWI duration (minutes) and T(rec) cooling rates (°C/min). RESULTS: Participants had similar exercise times (NOpads = 40.8 ± 4.9 minutes, PADS = 43.2 ± 4.1 minutes; t(17) = 2.0, P = .10), hypohydration levels (NOpads = 1.5% ± 0.3%, PADS = 1.6% ± 0.4%; t(17) = 1.3, P = .22), and thermal-sensation ratings (NOpads = 7.2 ± 0.3, PADS = 7.1 ± 0.5; P > .05) before CWI. The CWI duration (median [interquartile range]; NOpads = 6.0 [5.4] minutes, PADS = 7.3 [9.8] minutes; z = 2.3, P = .01) and T(rec) cooling rates (NOpads = 0.28°C/min ± 0.14°C/min, PADS = 0.21°C/min ± 0.11°C/min; t(17) = 2.2, P = .02) differed between uniform conditions. CONCLUSIONS: Whereas participants cooled faster in NOpads, we still considered the PADS cooling rate to be acceptable (ie, >0.16°C/min). Therefore, if clinicians experience difficulty removing PADS or CWI treatment is delayed, they may immerse fully equipped hyperthermic football players in CWI and maintain acceptable T(rec) cooling rates. Otherwise, PADS should be removed preimmersion to ensure faster body core temperature cooling.

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 uniform's 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.

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.

Response of thermocouples interfaced to electrothermometers when immersed in 5 water bath temperatures.

CONTEXT: Thermocouples and electrothermometers are used in therapeutic modality research. Until recently, researchers assumed that these instruments were valid and reliable. OBJECTIVE: To examine 3 different thermocouple types in 5 degrees C, 15 degrees C, 18.4 degrees C, 25 degrees C, and 35 degrees C water baths. DESIGN: Randomized controlled trial. SETTING: Therapeutic modality laboratory. INTERVENTION(S): Eighteen thermocouple leads were inserted through the wall of a foamed polystyrene cooler. The cooler was filled with water. Six thermocouples (2 of each model) were plugged into the 6 channels of the Datalogger and 6 randomly selected channels in the 2 Iso-Thermexes. A mercury thermometer was immersed into the water and was read every 10 seconds for 4 minutes during each of 6 trials. The entire process was repeated for each of 5 water bath temperatures (5 degrees C, 15 degrees C, 18.4 degrees C, 25 degrees C, 35 degrees C). MAIN OUTCOME MEASURE(S): Temperature and absolute temperature differences among 3 thermocouple types (IT-21, IT-18, PT-6) and 3 electrothermometers (Datalogger, Iso-Thermex calibrated from -50 degrees C to 50 degrees C, Iso-Thermex calibrated from -20 degrees C to 80 degrees C). RESULTS: Validity and reliability were dependent on thermocouple type, electrothermometer, and water bath temperature (P < .001; modified Levene P < .05). Statistically, the IT-18 and PT-6 thermocouples were not reliable in each electrothermometer; however, these differences were not practically different from each other. The PT-6 thermocouples were more valid than the IT-18s, and both thermocouple types were more valid than the IT-21s, regardless of water bath temperature (P < .001). CONCLUSIONS: The validity and reliability of thermocouples interfaced to an electrothermometer under experimental conditions should be tested before data collection. We also recommend that investigators report the validity, the reliability, and the calculated uncertainty (validity + reliability) of their temperature measurements for therapeutic modalities research. With this information, investigators and clinicians will be better able to interpret and compare results and conclusions.

Temperature measurement reliability and validity with thermocouple extension leads or changing lead temperature.

CONTEXT: Thermocouples' leads are often too short, necessitating the use of an extension lead. OBJECTIVE: To determine if temperature measures were influenced by extension-lead use or lead temperature changes. DESIGN: Descriptive laboratory study. SETTING: Laboratory. OTHER PARTICIPANTS: Experiment 1: 10 IT-21 thermocouples and 5 extension leads. Experiment 2: 5 IT-21 and PT-6 thermocouples. METHODS: In experiment 1, temperature data were collected on 10 IT-21 thermocouples in a stable water bath with and without extension leads. In experiment 2, temperature data were collected on 5 IT-21 and PT-6 thermocouples in a stable water bath before, during, and after ice-pack application to extension leads. RESULTS: In experiment 1, extension leads did not influence IT-21 validity (P  =  .45) or reliability (P  =  .10). In experiment 2, postapplication IT-21 temperatures were greater than preapplication and application measures (P < .05). CONCLUSIONS: Extension leads had no influence on temperature measures. Ice application to leads may increase measurement error.

Superficial moist heat's lack of influence on soleus function.

CONTEXT: It is reported that thermotherapy decreases motoneuron-pool recruitment. Any decrease in recruitment might have a significant impact on an athlete's ability to return to competition. OBJECTIVE: To determine whether moist heat application influences involuntary motoneuron-pool recruitment or voluntary plantar-flexion peak torque of the soleus muscle immediately or 30 min after application. DESIGN: A 3 x 3 crossover design. SETTING: Biomechanics laboratory. PARTICIPANTS: Eighteen healthy subjects with no history of lower extremity surgery or injury 12 months before the study volunteered. INTERVENTION: A series of short-duration, high-intensity stimuli was delivered to the tibial nerve to find the H(max) and M(max) measures. Immediately after the H(max) and M(max) measures, subjects were positioned on an isokinetic dynamometer where they performed 5 submaximal warm-up repetitions. Immediately after the warm-up, 5 maximum-intensity peak plantar-flexion torque repetitions were performed. After the dynamometer measures, subjects returned to the table, where a moist heat pack, no heat pack, or a dry nonheated heat pack was applied. MAIN OUTCOME MEASURES: H(max), M(max), peak plantar-flexion torque, surface temperature (degrees C), and ambient temperature (degrees C). RESULTS: Moist heat did not influence the H:M(max) ratio or peak plantar-flexion torque. Temperature increased with moist heat pack. Ambient temperature remained constant. CONCLUSIONS: Moist heat did not influence involuntary motoneuron-pool recruitment or voluntary peak plantar-flexion torque of the soleus muscle immediately or 30 min after application.

Reliability and validity of electrothermometers and associated thermocouples.

OBJECTIVE: Examine thermocouple model uncertainty (reliability+validity). DESIGN: First, a 3x3 repeated measures design with independent variables electrothermometers and thermocouple model. Second, a 1x3 repeated measures design with independent variable subprobe. INTERVENTION: Three electrothermometers, 3 thermocouple models, a multi-sensor probe and a mercury thermometer measured a stable water bath. MAIN OUTCOME MEASURES: Temperature and absolute temperature differences between thermocouples and a mercury thermometer. RESULTS: Thermocouple uncertainty was greater than manufactures'claims. For all thermocouple models, validity and reliability were better in the Iso-Themex than the Datalogger, but there were no practical differences between models within an electrothermometers. Validity of multi-sensor probes and thermocouples within a probe were not different but were greater than manufacturers'claims. Reliability of multiprobes and thermocouples within a probe were within manufacturers claims. CONCLUSION: Thermocouple models vary in reliability and validity. Scientists should test and report the uncertainty of their equipment rather than depending on manufactures' claims.

Are room temperature and thermal neutral synonymous terms? An investigation of common therapeutic modality control variables.

CONTEXT: Therapeutic modality control variables are thought to be thermal neutral, a term sometimes used interchangeably with room temperature. We question this common assumption. OBJECTIVE: To determine thermal neutrality of common therapeutic modality control variables. DESIGN: We performed 5 laboratory experiments, including (1) water temperature over 3 weeks in 3 different containers (glass, plastic, and polystyrene); (2) water temperature and volume of 4 beakers (2 insulated, 2 uninsulated) over 4 weeks, with 1 beaker of each type covered by polyethylene; and skin interface temperature of (3) a dry, nonheated hydrocollator pack held against the chest, (4) kitty litter applied to the knee, and (5) room-temperature ultrasound gel to the forearm. SETTING: Therapeutic modalities laboratory. PATIENTS OR OTHER PARTICIPANTS: College student volunteers were subjects in experiments 3, 4, and 5. MAIN OUTCOME MEASURE(S): We measured temperature and volume change. Data were evaluated using descriptive and interferential statistics. RESULTS: Water temperature plateaued significantly below room temperature. Temperatures significantly increased in all but the open, insulated container. Open containers plateaued at approximately 2 degrees C below room temperature and lost significant amounts of water; closed containers plateaued at room temperature with negligible water loss. In experiments 3 through 5, skin temperatures rose significantly during hydrocollator pack, kitty litter, and ultrasound gel application. CONCLUSIONS: Room-temperature water baths, dry hydrocollator packs, kitty litter, and ultrasound gel were not thermally neutral. Room temperature should not be used synonymously with thermal neutral. Care must be taken to ensure that control variables truly are controlled.

The uncertainty (validity and reliability) of three electrothermometers in therapeutic modality research.

CONTEXT: Data from electrothermometers are used to determine therapeutic modality usage, but the value of experimental results is only as good as the data collected. OBJECTIVE: To determine the reliability and validity of 3 electrothermometers from 2 manufacturers. DESIGN: A 3 x 4 x 17 factorial with repeated measures on 2 factors. Independent variables were trial (1, 2, 3), thermometer (mercury thermometer, Iso-Thermex calibrated from -50 degrees C to 50 degrees C, Iso-Thermex calibrated from -20 degrees C to 80 degrees C, and Datalogger), and time (17). SETTING: Human Performance Research Center. INTERVENTION(S): Eighteen thermocouples were inserted through the wall of a foamed polystyrene cooler, and 6 were connected to each of the 3 electrothermometers. The cooler was positioned on a stir plate and filled with room-temperature water (18.4 degrees C). A mercury thermometer was immersed into the water bath. Measurements of the water bath were taken every 10 seconds for three 3-minute trials. MAIN OUTCOME MEASURE(S): The temperature variability of 3 electrothermometers was taken from a calibrated mercury thermometer. RESULTS: The Iso-Thermex electrothermometers did not differ statistically from each other in uncertainty (validity error +/- reliability error = 0.06 degrees C +/- 0.03 degrees C +/- 0.03 degrees C +/- 0.02 degrees C, P < .05), but both differed from the Datalogger (0.64 degrees C +/- 0.20 degrees C, P < .05). The Datalogger temperature was consistently higher than the mercury thermometer temperature. CONCLUSIONS: The Iso-Thermex electrothermometers were more stable than the Datalogger, and values were within the published uncertainty (+/-0.1 degrees C) when used with PT-6 thermocouples. The Datalogger we used had an uncertainty of measurement greater than that indicated in the user's manual (approximately +/-0.52 degrees C). Uncertainty of +/-0.84 degrees C can significantly influence the interpretation of results when intramuscular temperature changes are usually less than 5 degrees C.