John P. Vardiman

Relationships between skinfold thickness and electromyographic and mechanomyographic amplitude recorded during voluntary and non-voluntary muscle actions

INTRODUCTION The purpose of this study was to examine possible correlations between skinfold thicknesses and the a terms from the log-transformed electromyographic (EMGRMS) and mechanomyographic amplitude (MMGRMS)-force relationships, EMG M-Waves, and MMG gross lateral movements (GLM). METHODS Forty healthy subjects performed a 6-s isometric ramp contraction from 5% to 85% of their maximal voluntary contraction with EMG and MMG sensors placed on the vastus lateralis (VL) and rectus femoris (RF). A single electrical stimulus was applied to the femoral nerve to record the EMG M-waves and MMG GLMs. Skinfold thickness was assessed at the site of each electrode. Pearsons product correlation coefficients were calculated comparing skinfold thicknesses with the a terms from the log-transformed EMGRMS-and MMGRMS-force relationships, EMG M-waves, and MMG GLMs. RESULTS There were no significant cor1relations (p>0.05) between the a terms and skinfold thicknesses for the RF and VL from the EMGRMS and MMGRMS-force relationships. However, there were significant correlations (p<0.05) between skinfold thicknesses and the EMG M-waves and MMG GLMs for the RF (r=-0.521, -0.376) and VL (r=-0.479, -0.484). DISCUSSION Relationships were only present between skinfold thickness and the amplitudes of the EMG and MMG signals during the non-voluntary muscle actions.

Instrument-assisted soft tissue mobilization: Effects on the properties of human plantar flexors

The effect of instrument-assisted soft tissue mobilization (ISTM) on passive properties and inflammation in human skeletal muscle has not been evaluated. Passive properties of muscle, inflammatory myokines and subjective reporting of functional ability were used to identify the effects of ISTM on the plantar flexors. 11 healthy men were measured for passive musculotendinous stiffness (MTS), passive range of motion (PROM), passive resistive torque (PASTQ) and maximum voluntary contraction peak torque (MVCPT) for plantar flexor muscles of the lower leg. Interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) were measured from muscle biopsies from the gastrocnemius, and subjective measurements of functional ability were taken using the perception of functional ability questionnaire (PFAQ). MTS, PROM, PRT and MVCPT were measured in the treatment leg (TL) and control leg (CL) before, immediately after, 24 h, 48 h and 72 h following IASTM. Biopsies for IL-6 and TNF-α and PFAQ responses were collected before as well as 24 h, 48 h and 72 h after IASTM. There were no significant differences in MTS, PROM, PASTQ, MVCPT, IL-6 and TNF-α between the TL or CL. A significant decrease in the perception of function and a significant increase in pain for the TL were found following IASTM.

Influence of the contractile properties of muscle on motor unit firing rates during a moderate-intensity contraction in vivo.

It is suggested that firing rate characteristics of motor units (MUs) are influenced by the physical properties of the muscle. However, no study has correlated MU firing rates at recruitment, targeted force, or derecruitment with the contractile properties of the muscle in vivo. Twelve participants (age = 20.67 ± 2.35 yr) performed a 40% isometric maximal voluntary contraction of the leg extensors that included linearly increasing, steady force, and decreasing segments. Muscle biopsies were collected with myosin heavy chain (MHC) content quantified, and surface electromyography (EMG) was recorded from the vastus lateralis. The EMG signal was decomposed into the firing events of single MUs. Slopes and y-intercepts were calculated for 1) firing rates at recruitment vs. recruitment threshold, 2) mean firing rates at steady force vs. recruitment threshold, and 3) firing rates at derecruitment vs. derecruitment threshold relationships for each subject. Correlations among type I %MHC isoform content and the slopes and y-intercepts from the three relationships were examined. Type I %MHC isoform content was correlated with MU firing rates at recruitment (y-intercepts: r = -0.577; slopes: r = 0.741) and targeted force (slopes: r = 0.853) vs. recruitment threshold and MU firing rates at derecruitment (y-intercept: r = -0.597; slopes: r = 0.701) vs. derecruitment threshold relationships. However, the majority of the individual MU firing rates vs. recruitment and derecruitment relationships were not significant (P > 0.05) and, thus, revealed no systematic pattern. In contrast, MU firing rates during the steady force demonstrated a systematic pattern with higher firing rates for the lower- than higher-threshold MUs and were correlated with the physical properties of MUs in vivo.

The change in motor unit firing rates at de-recruitment relative to recruitment is correlated with type I myosin heavy chain isoform content of the vastus lateralis in vivo.

To investigate the change in motor unit (MU) firing rates (FR) at de‐recruitment relative to recruitment and the relation to % type I myosin heavy chain isoform content (type I %MHC) of the vastus lateralis (VL) in vivo.

A reliable method for assessing rotational power.

Andre, MJ, Fry, AC, Heyrman, MA, Hudy, A, Holt, B, Roberts, C, Vardiman, JP, and Gallagher, PM. A reliable method for assessing rotational power. J Strength Cond Res 26(3): 720–724, 2012—Rotational core training is said to be beneficial for rotational power athletes. Currently, there has been no method proposed for the reliable assessment of rotational power. Therefore, our purpose was to determine the test-retest reliability of kinetic and kinematic rotational characteristics of a pulley system when performing a rotational exercise of the axial skeleton in the transverse plane to find out if this would be a reliable tool for evaluating rotational power. Healthy, college-aged men (n = 8) and women (n = 15) reported for 3 testing sessions. The participants were seated on a box, and they held the handle with both arms extended in front of their body, starting their motion with their torso rotated toward the machine. All the participants rotated their torso forcefully until they reached 180° of rotation, and they then slowly returned to the starting position, 3 times per trial, with 3 loads: 9% body weight (BW), 12% BW, and 15% BW. The repetition with the greatest power for each trial for each load was analyzed. The mean peak power repetition (watts) for all the subjects was 20.09 ± 7.16 (9% BW), 26.17 ± 8.6 (12% BW), and 30.74 ± 11.022 (15% BW) in the first training session and 22.3 ± 8.087 (9% BW), 28.7 ± 11.295 (12% BW), and 33.52 ± 12.965 (15% BW) in the second training session with intraclass correlation coefficients of 0.97 (9%BW), 0.94 (12%BW), and 0.95 (15%BW). When the participants were separated by sex, there were no significant differences between groups. Based on these results, it was found that a pulley system and an external dynamometer can be used together as a reliable research tool to assess rotational power.

Perception of Exercise-Induced Bronchoconstriction in College Athletes

BACKGROUND: Exercise-induced bronchoconstriction (EIB) can lead to long-term respiratory illness and even death. EIB prevalence rates are both high and variable in college athletes. Also, prevalence rates may be underestimated due to ineffective screening. The purpose of this study is to investigate the prevalence of EIB and the perceived impact of EIB in college athletes via a self-report questionnaire. METHODS: A self-report EIB questionnaire was administered to college athletes on 8 different sports teams. Information collected was used to identify athletes who self-reported: (1) a history of EIB and/or asthma, (2) respiratory symptoms during exercise, (3) medication use, and (4) concern about EIB. RESULTS: Results showed that 56 of 196 athletes (28.6%) self-reported a history of EIB or asthma. Over half (52%) reported a history of EIB/asthma or current EIB symptoms. Forty-six of the 140 athletes (32.9%) who did not report a history of EIB or asthma indicated symptoms of EIB during sports, training, or exercise. Fourteen of 56 athletes (25%) self-reporting a history of EIB or asthma did not report the use of a respiratory medication. Nineteen of 196 athletes (9.7%) reported being concerned that EIB was adversely affecting their sports performance. CONCLUSIONS: College athletes self-report a high prevalence of EIB or asthma. Although college athletes may not report a history of EIB or asthma, they indicate symptoms of EIB. A majority of athletes reported a history or current symptoms related to EIB or asthma. Many athletes with a history of EIB or asthma are not taking any asthma medication. Last, athletes report concern about EIB adversely affecting their sports performance. More work is needed using a combination of a screening questionnaire and standardized EIB testing to develop a validated tool for accurately screening and diagnosing EIB in college athletes.

Immunoendocrine alterations following Marine Corps Martial Arts training are associated with changes in moral cognitive processes

Combined physical and psychological stress events have been associated with exacerbated endocrine responses and increased alterations in immune cell trafficking when compared to exercise stress alone. Military training programs are rigorous in nature and often purposefully delivered in environments combining high levels of both physical and mental stress. The objective of this study was to assess physiological and cognitive changes following U.S. Marine Corps Martial Arts training. Seven active-duty, male Marines were observed during a typical Marine Corps Martial Arts training session. Immune parameters, including immunomodulatory cytokines, and hormone concentrations were determined from blood samples obtained at baseline, immediately post training (IP) and at 15min intervals post-training to 1h (R15, R30, R45, R60). Assessments of cognitive moral functioning (moral judgment and intent) were recorded at intervals during recovery. There were significant fluctuations in immunoendocrine parameters. Peak endocrine measures were observed within the IP-R15 time interval. Distributions of circulating immune cells were significantly altered with neutrophils and all lymphocyte subsets elevated at IP. IFN-γ and IL-17a exhibited small, non-significant, parallel increases over the recovery period. Moral functioning was informed by different social identities during the recovery resulting in changes in moral decision-making. These data demonstrate that the Marine Corps Martial Arts Program induces significant alterations in lymphocyte and leukocyte distributions, but does not shift the balance of Th1/Th2 cytokines or induce a systemic inflammatory response. The program does, however, induce alterations in moral decision-making ability associated with the observed endocrine responses, even suggesting a potential interaction between ones social identities and endocrine responses upon moral decision-making.

The influence of myosin heavy chain isoform content on mechanical behavior of the vastus lateralis in vivo

This study examined correlations between type I percent myosin heavy chain isoform content (%MHC) and mechanomyographic amplitude (MMGRMS) during isometric muscle actions. Fifteen (age=21.63±2.39) participants performed 40% and 70% maximal voluntary contractions (MVC) of the leg extensors that included increasing, steady force, and decreasing segments. Muscle biopsies were collected and MMG was recorded from the vastus lateralis. Linear regressions were fit to the natural-log transformed MMGRMS-force relationships (increasing and decreasing segments) and MMGRMS was selected at the targeted force level during the steady force segment. Correlations were calculated among type I%MHC and the b (slopes) terms from the MMGRMS-force relationships and MMGRMS at the targeted force. For the 40% MVC, correlations were significant (P<0.02) between type I%MHC and the b terms from the increasing (r=-0.804) and decreasing (r=-0.568) segments, and MMGRMS from the steady force segment (r=-0.606). Type I%MHC was only correlated with MMGRMS during the steady force segment (P=0.044, r=-0.525) during the 70% MVC. Higher type I%MHC reduced acceleration in MMGRMS (b terms) during the 40% MVC and the amplitude during the steady force segments. The surface MMG signal recorded during a moderate intensity contraction provided insight on the contractile properties of the VL in vivo.

Intramuscular heating through fluidotherapy and heat shock protein response.

CONTEXT Therapeutic modalities that can increase intramuscular temperature commonly are used to treat injuries in the clinical setting. Researchers recently have suggested that the physiologic changes occurring during an increase in temperature also could provide a cytoprotective effect for exercise-induced muscle damage. OBJECTIVE(S) To determine if the Fluidotherapy treatment increases the inducible expression of heat shock protein (HSP), to identify the rate of heating that occurs in the lower extremity with Fluidotherapy treatment, and to evaluate the relationship between the inducible expression of HSP and temperature. DESIGN Controlled laboratory study. SETTING Laboratory. PATIENTS OR OTHER PARTICIPANTS Six male (age = 21.67 ± 1.63 years, height = 180.09 ± 4.83 cm, mass = 87.60 ± 10.51 kg) and 6 female (age = 24.60 ± 4.59 years, height = 151.05 ± 35.76 cm, mass = 55.59 ± 14.58 kg) college-aged students. INTERVENTION(S) One lower extremity was randomly selected to receive the heat treatment, and the other extremity received no treatment. MAIN OUTCOME MEASURE(S) We measured intramuscular temperature every 10 minutes, determining peak intramuscular temperature by 2 identical sequential measurements, and we analyzed the time to peak temperature. We analyzed the amount of HSP70 expression and HSP27P:T (ratio of HSP27 to the total HSP27 expression) in the gastrocnemius and soleus muscles and measured baseline skinfold thickness and estradiol levels. RESULTS Fluidotherapy increased intramuscular temperature by 5.66 ± 0.78°C (t11 = 25.67, P < .001) compared with baseline temperature, with a peak temperature of 39.08°C ± 0.39°C occurring at 84.17 ± 6.69 minutes. We did not find a heat treatment effect for HSP70 or HSP27P:T in the gastrocnemius or soleus muscles (P > .05). Peak temperature and the percentage change of HSP70 were positively correlated for the gastrocnemius and soleus muscles (P < .05). We found no other correlations for skinfold thickness, sex, or estradiol levels (P > .05). No effect of sex for skinfold thickness or estradiol levels at baseline was discovered (P > .05). CONCLUSIONS This Fluidotherapy protocol increased the intramuscular temperature to a therapeutic level; however, it did not stimulate inducible HSP70 or HSP27P:T in the soleus and gastrocnemius muscles regardless of sex or skinfold thickness. These data confirmed that Fluidotherapy is an effective heating modality but suggested it is not an effective method for stimulating an HSP response in the lower limb.

T Cell Activation and Proliferation Following Acute Exercise in Human Subjects is Altered by Storage Conditions and Mitogen Selection

Recent work investigating exercise induced changes in immunocompetence suggests that some of the ambiguity in the literature is resultant from different cell isolation protocols and mitogen selection. To understand this effect, we compared post-exercise measures of T cell activation and proliferation using two different stimulation methods (costimulation through CD28 or stimulation with phytohaemagglutinin [PHA]). Further, we investigated whether exercise induced changes are maintained when T cell isolation from whole blood is delayed overnight in either a room temperature or chilled (4°C) environment. As expected, an increased proliferation response was observed post-exercise in T cells isolated from whole blood of previously trained individuals immediately after blood collection. Also, cells stimulated with PHA after resting overnight in whole blood were not adversely impacted by the storage conditions. In contrast, allowing cells to rest overnight in whole blood prior to stimulation through CD28, lessened the proliferation observed by cells following exercise rendering both the room temperature and chilled samples closer to the results seen in the control condition. Changes in early markers of activation (CD25), followed a similar pattern, with activation in PHA stimulated cells remaining fairly robust after overnight storage; whereas cell activation following stimulation through CD3+CD28 was disproportionately decreased by the influence of overnight storage. These findings indicate that decisions regarding cell stimulation methods need to be paired with the timeline for T cell isolation from whole blood. These considerations will be especially important for field based studies of immunocompetence where there is a delay in getting whole blood samples to a lab for processing as well as clinical applications where a failure to isolate T cells in a timely manner may result in loss of the response of interest.