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Background: Within the last two decades, attitudes have shifted from considering sports-related concussion as an insignificant minor injury with no long-term repercussions to a potentially serious brain injury garnering attention from media, clinicians, researchers, and the general public., Objectives: To conduct a case study to determine the underlying cause of persistent issues suspected to be associated with a history of sports-related concussion., Protocol: Participant A underwent neurophysiological testing following the Neary protocol (assessment of cerebrovascular and cardiovascular variables), comprehensive concussion assessment at a dedicated sports concussion clinic (history, neurological assessment, cervical spine screening, vestibulo-ocular screening, SCAT-5, and exercise testing), referral to a neurologist, structural MRI scan, and referral for specialised assessment at a dedicated dizziness and balance centre., Results: Despite a history of multiple sports-related concussions, Participant A's persistent symptom reports were associated with peripheral vestibular dysfunction and otolithic dysfunction seemingly unrelated to his concussion history., Discussion: Lessons from Participant A's case study showed that on-going symptoms that patients may associate with the effects of concussions may instead be due to unrelated causes that share similar symptomology., Conclusion: This research exemplifies the importance of a multi-disciplinary assessment using a repeated testing protocol.

Finding sensitive and specific markers for sports-related concussion is both challenging and clinically important. Such biomarkers might be helpful in the management of patients with concussion (i.e. diagnosis, monitoring and risk prediction). Among many parameters, blood flow-pressure metrics and heart rate variability (HRV) have been used to gauge concussion outcomes. Reports on the relation between HRV and both acute and prolonged concussion recovery are conflicting. While some authors report on differences in the low-frequency (LF) component of HRV during postural manipulations and postexercise conditions, others observe no significant differences in various HRV measures. Despite the early success of using the HRV LF for concussion recovery, the interpretation of the LF is debated. Recent research suggests the LF power is a net effect of several intrinsic modulatory factors from both sympathetic and parasympathetic branches of the autonomic nervous system, vagally mediated baroreflex and even some respiratory influences at lower respiratory rate. There are only a few well-controlled concussion studies that specifically examine the contribution of the autonomic nervous system branches with HRV for concussion management. This study reviews the most recent HRV- concussion literature and the underlying HRV physiology. It also highlights cerebral blood flow studies related to concussion and the importance of multimodal assessment of various biological signals. It is hoped that a better understanding of the physiology behind HRV might generate cost-effective, repeatable and reliable protocols, all of which will improve the interpretation of HRV throughout concussion recovery., (© 2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.)

Background: Clinicians typically rely on neuropsychological and balance tests to track concussion recovery. The aforementioned tests imply impairments that are based on performance, but these tests do not directly measure brain physiology throughout concussion recovery. Because of these issues, an objective biomarker that can index severity and the recovery timeline is needed. Moreover, the number of concussions occurring at a recreational level requires the biomarker to be easily administered in a cost effective manner, and the results easily interpreted., Methods: To address these issues, near-infrared spectroscopy was used to assess the relative changes in oxy (HbO 2 )- and deoxyhaemoglobin and the associated standard deviations (SD) in the prefrontal cortex. Resting haemoglobin, and haemoglobin changes in response to hypercapnia (five repeated 20s breath holds), was measured in all participants. Data were aggregated into healthy baselines (n = 115), and concussed participants on days 1-3 (n = 14), 4-6 (n = 8), and 7-14 (n = 11). The data were statistically compared using a 1 × 4 ANOVA., Results: Resting HbO 2 values progressively lowered from days 1-3 to 7-14 (with no differences compared to controls). The second major finding showed that hypercapnic HbO 2 SD was significantly lower than resting values on days 1-3 and 4-6, but reversed back towards the healthy control group on day 7-14., Conclusion: Monitoring cerebral oxygenation changes is a viable biomarker to assess the physiological state of the brain following concussion., (© 2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.)

Abnormal cerebrospinal fluid (CSF) pulsatility has been implicated in patients suffering from various diseases, including multiple sclerosis and hypertension. CSF pulsatility results in subarachnoid space (SAS) width changes, which can be measured with near-infrared transillumination backscattering sounding (NIR-T/BSS). The aim of this study was to combine NIR-T/BSS and wavelet analysis methods to characterise the dynamics of the SAS width within a wide range of frequencies from 0.005 to 2 Hz, with low frequencies studied in detail for the first time. From recordings in the resting state, we also demonstrate the relationships between SAS width in both hemispheres of the brain, and investigate how the SAS width dynamics is related to the blood pressure (BP). These investigations also revealed influences of age and SAS correlation on the dynamics of SAS width and its similarity with the BP. Combination of NIR-T/BSS and time-frequency analysis may open up new frontiers in the understanding and diagnosis of various neurodegenerative and ageing related diseases to improve diagnostic procedures and patient prognosis.

Purpose: The purpose of the present study was to identify the risk factors for major complications developing during the operative treatment of mandibular fractures., Patients and Methods: We conducted a retrospective medical record review of patients who had undergone open reduction, internal fixation of mandibular fractures from August 1, 2012 to December 31, 2014 at a large, urban teaching hospital and level 1 trauma center. The outcome variable of interest was major complications, defined as the occurrence of any one of the following events: hospital readmission, return to the operating room, and a prolonged, unexpected postoperative stay. Multiple demographic, social, medical, injury-related, and treatment-related variables were recorded during the medical record review. The relationships between these variables and our outcome variable were analyzed using univariate and multivariable logistic regression analyses., Results: A total of 317 patients met the inclusion criteria. The hospital readmission rate was 7.2%, the reoperation rate was 9.5%, and the rate of unplanned, prolonged admission was 0.6%, for a total major complication rate of 11.4%. Eight variables reached statistical significance in their association with the occurrence of major complications. These were the presence of medical comorbidities, a diagnosis of depression, a diagnosis of a psychiatric disorder, incarceration, interpersonal violence as a mechanism of injury, the presence of a left angle fracture, the removal of a tooth in the line of fracture, and patient noncompliance. On multivariable analysis, patient noncompliance, depression, the presence of a left angle fracture, and the removal of a tooth in the line of fracture continued to have statistically significant associations with the occurrence of major complications., Conclusions: The identification of risk factors for the development of complications in mandibular trauma is a primary concern for surgeons in the modern healthcare system. The present study identified a number of variables significantly associated with an increased risk of the occurrence of major complications, and special consideration should be given to patients with these risk factors., (Copyright © 2016 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

Primary Objective: To assess and compare the parasympathetic state of individuals in healthy vs concussion groups, by measuring cardiovascular metrics under resting and baroreflex conditions using a squat-stand manoeuvre., Research Design: This was a retrospective mixed-method study, with participants who sustained a medically diagnosed sport concussion (n = 12), being tested within 72-hours post-injury., Methods and Procedures: Participant's heart rate (Electrocardiogram, ECG) and blood pressure (finger plethysmography) data was collected during rest and during 10-second squat-stands (10SS, 0.05 Hz). Blood pressure and heart rate standard deviation data was analysed in the 0-5 seconds and 6-10 seconds periods of squatting and standing. Resting and baroreflex ECG data were analysed via Fourier Transformations for %Low Frequency and %High Frequency (%LF and %HF)., Results: The control group alleviated more pressure and had a significantly higher standard deviation of heart rate during the 6-10 seconds of squatting (p < 0.05). Overall heart rate standard deviation in the concussion group was significantly lower than healthy controls when standing (p < 0.05). There were no differences in %LF and % HF between groups or between rest and 10SS., Conclusion: This study provides preliminary evidence that autonomic function is dysregulated following mTBI within the initial 72 hours of injury.

Introduction: Night vision goggles (NVG) are linked to increased neck muscle activation and pain. Counterweights (NVGcw) are hypothesized to mitigate these effects. The purpose of this study was to investigate the muscular response to varying helmet loads and postures., Methods: Volunteering from a representative squadron were 16 male helicopter aviators (pilots, N = 9; flight engineers, N = 7). Subjects performed head movements to assume nine different postures (three directions: left, center, and right, at three different levels: down, level, and up) with four different head loads (no helmet; helmet only; NVG; and NVGcw) in randomized order. Subjects were provided real time visual guidance and feedback while assuming the appropriate posture in a cockpit seat in a laboratory setting. Neck muscle activation was assessed with electromyography (EMG) of four different muscle groups, bilaterally, including the sternocleidomastoid, splenius capitis, and mid and lower trapezius., Results: Two- to fourfold increases in muscle activation were observed in postures to the left (down, level, and up) while subjects wore either the NVG or NVGcw as compared to the baseline of no helmet. This was most prevalent in smaller muscle groups (i.e., the sternocleidomastoid and splenius capitis) as compared to larger muscle groups (i.e., the mid and lower trapezius)., Discussion: The use of NVGcw did not decrease neck muscle activity as compared to NVG only, particularly when the head posture moved the field of view below the horizon. This suggests interventions to decrease neck muscle activity and fatigue in military helicopter aircrew using NVG should focus on task specific guidelines with respect to countermeasures.

Previous research demonstrated higher maximal voluntary contraction (MVC) force with upright vs. inverted positions in untrained individuals. The purpose was to determine the effects of inversion on force, activation, and cardiovascular responses before and following fatigue in trained individuals. Twelve male athletes completed two trials: upright and inverted seated positions. At baseline (upright), either leg extension (LE) or elbow flexion (EF) evoked contractile properties and MVCs were performed. LE and EF contractions were randomly allocated and performed in separate sessions. The subject was then positioned for 150s in each posture, followed by a 30s MVC (MVC30). During each trial, stroke volume (SV), cardiac output (Q), heart rate (HR), time and frequency domain HR variability measures and mean arterial blood pressure (MAP) measurements were recorded. ANOVA showed no statistical differences in EF MVC force, but a tendency (p=.12) for LE MVC decline with inversion vs. upright. Evoked resting (p=.1) and potentiated peak twitch (p=.04) force were increased with inverted LE but tended to diminish with inverted EF (p=.06 and p=.1). Force-fatigue, electromyography-fatigue relationships and HR variability during MVC30 fatigue were not affected. HR and Q were significantly (p=.01) lower with inversion following both LE and EF fatigue. Compared to the significant inversion-induced changes associated with untrained individuals in previously published studies, the lack of postural changes in resting force and CV measures may demonstrate that highly trained individuals adapt better to inversion., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Introduction: To address the high prevalence of neck dysfunction in helicopter aircrew, a 12-wk training program was designed to examine the effects on neck muscular strength and endurance., Methods: Subjects were recruited from Canadian Forces (CF) helicopter aircrew and randomized into either a neck coordination training program (CTP; N = 10), an endurance training program (ETP; N = 11), or a nontreatment control (CON; N = 8). Baseline assessments determined maximal voluntary contraction (MVC) strength and endurance capacity using a submaximal contraction to fatigue at 70% of their MVC for extension, flexion, and left (Ltflx) and right (Rtflx) lateral flexion. The ETP subjects performed dynamic contractions at 30% of their MVC in the four testing directions using a head harness and Thera-band tubing. The CTP consisted of exercises that focused on strengthening the deep cervical musculature using the mass of the head as resistance and progressing to exercises that incorporated the superficial cervical muscles., Results: Post-intervention, the ETP achieved the only statistically significant increase in maximal force when compared to the CON (14.4%). Improved times to fatigue were achieved by the CTP for flexion (26.34 +/- 20.72 s), Ltflx (23.54 +/- 13.94 s), and Rtflx (28.72 +/- 4.88 s)., Conclusion: The provision of an ETP and CTP resulted in a positive trend toward improved maximal force and muscular endurance. The greatest improvements in endurance and strength were found for those subjects assigned to the CTP treatment. Our research demonstrates the importance of including a designed and supervised training program into the daily routine of helicopter aviators.

Primary Objective: This study examined the effects of mild traumatic brain injury (mTBI) on cerebrovascular reactivity (CVR)., Research Design: A repeated measures design was used to examine serial changes in CVR., Methods and Procedures: Twenty subjects who recently suffered a mTBI were subjected to a respiratory challenge consisting of repeated 20 s breath-holds (BH) and hyperventilations (HV). Testing occurred on days 2 (D2), 4 (D4) and 8 (D8) post-injury as well as a baseline (BASE) assessment (after return-to-play). Transcranial Doppler was used to assess mean cerebral blood velocity (vMCA) and expired gas analysis provided end-tidal carbon dioxide (PETCO2) levels., Results: There was no significant difference in resting vMCA across all testing days for mTBI. No significant differences in PETCO2 were found throughout the testing protocol. A significant effect (p < 0.001) of testing day on vMCA was found during BH and HV challenges for mTBI. Post-hoc analysis revealed significant differences (p < 0.05) in vMCA between D2 and the other testing days., Conclusions: These data suggest that, following mTBI: (1) CVR is not impaired at rest; (2) CVR is impaired in response to respiratory stress; and (3) the impairment may be resolved as early as 4 days post-injury.

Ballistocardiography (BCG) is a non-invasive technology that has been used to record ultra-low-frequency vibrations of the heart allowing for the measurement of cardiac cycle events including timing and amplitudes of contraction. Recent developments in BCG have made this technology simple to use, as well as time- and cost-efficient in comparison with other more complicated and invasive techniques used to evaluate cardiac performance. Recent technological advances are considerably greater since the advent of microprocessors and laptop computers. Along with the history of BCG, this paper reviews the present and future potential benefits of using BCG to measure cardiac cycle events and its application to clinical and applied research., (© 2012 The Authors Clinical Physiology and Functional Imaging © 2012 Scandinavian Society of Clinical Physiology and Nuclear Medicine.)

Introduction: While many studies have investigated neck strain in helicopter aircrew, no one study has used a comprehensive approach involving multivariate analysis of questionnaire data in combination with physiological results related to the musculature of the cervical spine., Methods: There were 40 aircrew members who provided questionnaire results detailing lifetime prevalence of neck pain, flight history, physical fitness results, and physiological variables. Isometric testing data for flexion (Flx), extension (Ext), and right (RFlx) and left (LFlx) lateral flexion of the cervical spine that included maximal voluntary contraction (MVC) force and submaximal exercise at 70% MCV until time-to-fatigue (TTF) was also collected. Muscles responsible for the work performed were monitored with electromyography (EMG) and near-infrared spectroscopy (NIRS) and the associated ratings of perceived exertion (RPE) were collected simultaneously. Results were compiled and analyzed by logistic regression to identify the variables that were predictive of neck pain., Results: While many variables were included in the logistic regression, the final regression equation required two, easy to measure variables. The longest single night vision goggle (NVG) mission (NVGmax; h) combined with the height of the aircrew member in meters (m) provided an accurate logistic regression equation for approximately one-half of our sample (N = 19). Cross-validation of the remaining subjects (N = 21) confirmed this accuracy., Conclusion: Our regression equation is simple and can be used by global operational units to provide a cursory assessment without the need for acquiring specialized equipment or training.

Introduction: Neck pain in the Canadian Forces (CF) helicopter community related to night vision goggles (NVG) use is of growing concern. This study compares symptom reports and physiological responses and provides comparison between pilots and flight engineers (FE)., Methods: Aircrew (22 pilots, 18 FE) detailed their neck pain symptoms, flight history, and fitness results. Subjects participated in isometric testing of flexion, extension, and right and left lateral flexion of the cervical spine that included maximal voluntary contraction (MVC) force and 70% MVC endurance trials. Cervical muscles were monitored with electromyography (EMG) and near-infrared spectroscopy (NIRS) and ratings of perceived exertion (RPE) were collected., Results: Of the aircrew, 53% reported neck pain. No significant differences were observed between pilots and FE with respect to frequency of reporting pain. MVC results were found to differ when extension was compared to flexion and when left flexion was compared to right flexion. Time-to-fatigue (TTF) results were obtained and no significant differences were found between groups. EMG assessment of normalized median frequency indicated fatigue onset while NIRS results changed from baseline for most variables during the time-to-fatigue trials., Discussion: Neck pain in Canadian Forces helicopter crewmembers continues to be an occupational concern. No significant differences between FE and pilot results were found, suggesting that the cause of the pain is likely something common to both aircrew during flight.

Purpose: This study evaluated cerebrovascular reactivity (CVR) after a sport-induced concussion, also called mild traumatic brain injury (mTBI), by monitoring middle cerebral artery blood velocity (vMCA) with transcranial Doppler ultrasonography and simultaneous end-tidal carbon dioxide (PETCO(2)) measurements., Methods: Thirty-one athletes (16-25 yr old) participated in this study. The participants were divided into two groups-healthy (n = 21) and mTBI (n = 10). Participants in the mTBI group suffered an mTBI within the last 7 d (x- = 4.5 ± 1.1 d). Outcome measures included vMCA and PETCO(2) in response to breath holding (5 × 20 s, 40-s rest) and hyperventilation (5 × 20 s, 40-s rest)., Results: Resting vMCA values between groups were not significantly different. Percentage change of vMCA was significantly different after the recovery period of the second hyperventilation (P = 0.034). mTBI subjects failed to return to resting levels after each breath hold. PETCO(2) changes mirrored the vMCA changes., Conclusions: These data suggest that normal CVR responses may be disrupted in the days immediately after occurrence of mTBI. Transcranial Doppler ultrasonography combined with expired gas measurements provides a useful method for assessing CVR impairment after mTBI. Further research, including serial monitoring after mTBI and analysis of CVR response to exercise, is warranted before any firm conclusions can be drawn.

Neck pain is a growing aeromedical concern for military forces on an international scale. Neck pain prevalence in the global military helicopter community has been reported in the range of 56.6-84.5%. Despite this high prevalence, historically, research examining helicopter aircrews has focused predominantly on low back pain. A number of recent studies have emerged examining flight-related factors that are hypothesized to contribute to the development of flight-related neck pain. Loading factors such as the posture adopted during flight, use of night vision goggles, and vibration have all been found to contribute to neck pain and muscular fatigue. Prolonged or repeated exposureto these loading factors has been hypothesized to perpetuate or contribute to the development of neck pain. Despite the high number of helicopter aircrew personnel that suffer from neck pain, very few individuals seek treatment for the disorder. The focus of medical personnel should, therefore, be directed toward a solution that addresses not only the issue of muscular fatigue, but the hesitancy to seek treatment. Previous research in military and civilian populations have used exercise therapy as a treatment modality for neck pain and have found improved endurance capacity in the neck musculature and reduced self-reported neck pain.

Mild traumatic brain injury (mTBI) or sport-induced concussion has recently become a prominent concern not only in the athletic setting (i.e. sports venue) but also in the general population. The majority of research to date has aimed at understanding the neurological and neuropsychological outcomes of injury as well as return-to-play guidelines. Remaining relatively unexamined has been the pathophysiological aspect of mTBI. Recent technological advances including transcranial Doppler ultrasound and near infrared spectroscopy have allowed researchers to examine the systemic effects of mTBI from rest to exercise, and during both asymptomatic and symptomatic conditions. In this review, we focus on the current research available from both human and experimental (animal) studies surrounding the pathophysiology of mTBI. First, the quest for a unified definition of mTBI, its historical development and implications for future research is discussed. Finally, the impact of mTBI on the control and regulation of cerebral blood flow, cerebrovascular reactivity, cerebral oxygenation and neuroautonomic cardiovascular regulation, all of which may be compromised with mTBI, is discussed., (© 2010 The Authors. Clinical Physiology and Functional Imaging © 2010 Scandinavian Society of Clinical Physiology and Nuclear Medicine.)

We investigated the role of passive hyperthermia upon motor unit activation and prefrontal cortex oxygenation. Six healthy males were passively heated, using a liquid conditioning garment in a hot environment (35 degrees C, 50% relative humidity). Maximal force output and voluntary activation were examined during a 10 s maximal isometric knee extension. Of the initial 6 subjects, 1 experienced syncope at a rectal temperature (Tre) of 38.0 degrees C and was removed from the study. The remaining 5 subjects completed heating and testing to a Tre of 38.5 degrees C (n = 1), 39.0 degrees C (n = 3), or 39.5 degrees C (n = 1), and then were cooled back to baseline. Force production decreased from 553 +/- 133 to 430 +/- 176 N (p < 0.01) with passive heating, as did voluntary activation (from 90 +/- 5% to 84 +/- 7%). Percent heart rate reserve increased from 8 +/- 5% to 59 +/- 3% before returning to 4 +/- 8% (p < 0.001). Although mean arterial pressure remained unchanged, there were significant decreases in diastolic blood pressure with heating (80 +/- 3 to 63 +/- 8 mm Hg). Passive heating did not alter prefrontal cortex oxygenation, but cooling back to baseline core temperature attenuated cerebral oxygenated and total hemoglobin levels (p < 0.05). Passive heating to the point of voluntary exhaustion elevated cardiovascular and thermal strain and subjective perceptions of thermal discomfort. However, while this resulted in a marked decrement in maximal isometric force production and central voluntary activation, no concomitant changes in cerebral oxygenation were observed, suggesting that overall cerebrovascular regulation was maintained.

Introduction: Documented neck strain among military helicopter aircrew is becoming more frequent and many militaries use helicopters that provide pilots with the option of sitting in the left or right cockpit seat during missions., Purpose: The purpose of this study was to use near infrared spectroscopy (NIRS) to investigate the physiological changes in trapezius muscle oxygenation and blood volume during night vision goggle (NVG) flights as a function of left and right cockpit seating., Methods: There were 25 pilots who were monitored during NVG flight simulator missions (97.7 +/- 16.1 min). Bilateral NIRS probes attached to the trapezius muscles at C7 level recorded total oxygenation index (TOI, %), total hemoglobin (tHb), oxyhemoglobin (Hbo2), and deoxyhemo-globin (HHb)., Results: No significant differences existed between variables for pilots seated in the right cockpit seat as compared with the pilots seated in the left cockpit seat in either trapezius muscle (pTOI = 0.72; ptHb = 0.72; pHbo2 = 0.57; pHHb = 0.21)., Conclusion: Alternating cockpit seats on successive missions is not a means to decrease metabolic stress for helicopter pilots using NVG. This suggests that cockpit layout and location of essential instruments with respect to the horizontal and the increased head supported mass of the NVG may be important factors influencing metabolic stress of the trapezius muscle.

Introduction: This study examined metabolic and hemodynamic responses during night vision goggle (NVG) induced neck strain among military helicopter pilots. We hypothesized that near infrared spectroscopy (NIRS) would be capable of identifying metabolic differences in the trapezius muscles of pilots between simulated flights with and without NVG., Methods: There were 33 pilots who were monitored on consecutive days during Day and NVG flight simulator missions. NIRS probes were attached bilaterally to the trapezius muscles at the C7 level to record total oxygenation index (TOI, %), total hemoglobin (tHb), oxyhemoglobin (HbO2), and deoxyhemoglobin (HHb)., Results: Significant differences in tHb were found between Day (0.51+/-2.31 micromol x cm (-1)) and NVG (4.14 +/- 2.74 micromol x cm(-1)) missions, and for HbO2 (Dayend 2.63+/-1.64 micromol x cm(-1); NVGend 5.77+/-1.98 micromol x cm(-1)). Significant left and right side differences between Day and NVG were found for tHb (NVGleit -1.83+/-2.55; NVGright 10.45+/-2.86 micromol x cm(-1)), HbO2 (NVGleft 1.77+/-1.90; NVGright 9.95+/-2.07 micromol x cm(-1)), and HHb (Dayleft -1.84+/-0.95; Dayright -2.32+/-0.87 micromol x cm (-1); NVGleft -3.60+/-1.05 micromol x cm(-1); NVGright 0.49+/-1.16 micromol x cm(-1)., Discussion: These results support NIRS's utility in assessing the significant metabolic and hemodynamic effects of NVG on neck musculature during real-time missions for 1) left and right side differences; and 2) Day vs. NVG missions. The additional mass of the NVG equipment does increase the metabolic stress of these muscles during simulated missions.

Background: Biering-Sørenson (1984) found that individuals with less lumbar extensor muscle endurance had an increased occurrence of first episode low back pain. As a result, back endurance tests have been recommended for inclusion in health assessment protocols. However, different studies have reported markedly different values for endurance times, leading some researchers to believe that the back is receiving support from the biceps femoris and gluteus maximus. Therefore, this study was designed to examine the haemodynamic and neuromuscular activity of the erector spinae, biceps femoris, and gluteus maximus musculature during the Biering-Sørenson Muscular Endurance Test (BSME)., Methods: Seventeen healthy individuals and 46 individuals with chronic low back pain performed the Biering-Sørenson Muscular Endurance Test while surface electromyography was used to quantify neuromuscular activity. Disposable silver-silver-chloride electrodes were placed in a bipolar arrangement over the right or left biceps femoris, gluteus maximus, and the lumbosacral paraspinal muscles at the level of L3. Near Infrared Spectroscopy was used simultaneously to measure tissue oxygenation and blood volume changes of the erector spinae and biceps femoris., Results: The healthy group displayed a significantly longer time to fatigue (Healthy: 168.5s, LBP: 111.1s; p < or = 0.05). Significant differences were shown in the median frequency slope of the erector spinae between the two groups at 90-100% of the time to fatigue while no significant differences were noted in the haemodynamic data for the two groups., Conclusion: Although the BSME has been recognized as a test for back endurance, individuals with chronic LBP appear to incorporate a strategy that may help support the back musculature by utilizing the biceps femoris and gluteus maximus to a greater degree than their healthy counterparts.

BACKGROUND: This study examined muscle deoxygenation trends before and after a 7-day taper using non-invasive near infrared spectroscopy (NIRS). METHODS: Eleven cyclists performed an incremental cycle ergometer test to determine maximal oxygen consumption (VO2max = 4.68 +/- 0.57 L.min-1) prior to the study, and then completed two or three high intensity (85-90% VO2max) taper protocols after being randomly assigned to a taper group: T30 (n = 5), T50 (n = 5), or T80 (n = 5) [30%, 50%, 80% reduction in training volume, respectively]. Physiological measurements were recorded during a simulated 20 km time trials (20TT) performed on a set of wind-loaded rollers. RESULTS AND DISCUSSION: The results showed that the physiological variables of oxygen consumption (VO2), carbon dioxide (VCO2) and heart rate (HR) were not significantly different after tapering, except for a decreased ventilatory equivalent for oxygen (VE/VO2) in T50 (p

This study examined the utility of electromyography and near-infrared spectroscopy (NIRS) in assessing m. erector spinae activity during the Biering-Sorensen Back Muscle Endurance (BSME) test. Six men and four women (27.0 +/- 7.1 years of age) performed the BSME test (time = 131.5 +/- 43.5 s). EMG was used to quantify neuromuscular activity of the right and left side at the L3 level, and root mean square was scaled for maximum value at the start of the exercise. NIRS was used to evaluate blood volume (BV) and oxygenation (OX) simultaneous with EMG bilaterally at the L3 level. There was a decrease to 49+/- 8% of initial median frequency (mean= 83 Hz) on both right and left sides when the exercise was 90% complete, and the slope of the median frequency/time relationship was significantly related to BSME time (r = 0.82). Group means for BV increased during back exercise while OX decreased and was significantly different between right and left sides of the lower back. However, large OX response differences among individuals and between right and left sides were noted. OX and median frequency were moderately related (r = 0.27-0.38). It appears that NIRS combined with EMG is a promising tool for assessing localized metabolic and neuromuscular activity during static contractions of the lower back.

Over the past 15 years the use of near infrared spectroscopy in exercise and sports science has increased exponentially. The majority of these studies have used this noninvasive technique to provide information related to tissue metabolism during acute exercise. This has been undertaken to determine its utility as a suitable tool to provide new insights into the heterogeneity and regulation of local tissue metabolism, both in cerebral and skeletal muscle tissue. In the accompanying articles in this symposium, issues related to the principles, techniques, limitations (Ferrari et al., 2004), and reliability and validity of NIRS in both cerebral and skeletal muscle tissue (Bhaambhani, 2004), mostly during acute exercise, have been addressed and will not be discussed here. Instead, the present paper will focus specifically on the application of NIRS to exercise sports science, with an emphasis on how this technology has been applied to exercise training and sport, and how it can be used to design training programs for athletes.

This study examined the effects of different 7-day taper protocols on simulated 20-km time trials (20TT). Following 3 weeks of baseline training, 11 male cyclists (.VO2max = 4.78 +/- 0.66 L.min-1) were randomly assigned to one of three stepwise reduction tapers in which training volume was reduced by 30% (T30, n = 5), 50% (T50, n = 6), or 80% (T80, n = 6) of baseline training with intensity (85% .VO2max) maintained. Cardiorespiratory measurements were collected every 5 km during the 20TT. Results revealed a significant (5.4%, 0.05) improvement in 20TT performance in the T50 protocol with concomitant increases in .VO2 and O2 pulse. No significant differences were found in T30 or T80. These results showed that a moderate (50%) reduction in weekly training volume appeared to be optimal in terms of enhancing performance. This confirms the contention that proper placement of training volume during tapering, while maintaining exercise intensity, can elicit performance improvements.

This study examined the effects of a 15-day cessation of training on maximal oxygen consumption and selected physiological variables (maximal heart rate, cardiac output [Q], stroke volume [SV], arteriovenous oxygen difference [(a-v)O2 diff], blood plasma concentration) in 15 women middle-distance competitive runners (.VO2max: 49.8 +/- 1.1 ml.kg(-1).min(-1)). Subjects were randomly assigned to a cessation training (CT, n = 7) or maintenance training (MT, n = 8) group and tested every 5 days. Q was measured by CO2 rebreathing from which SV and (a-v)O2 diff were calculated. No significant changes were found at day 5. After 10 days there was a significant decrement in .VO2max (3.8 ml.kg(-1).min(-1)) in the CT group, being significantly lower than MT but no changes thereafter in any physiological variables. Performance (2,400 m) times did not change for MT but was significantly slower (21.5 +/- 7.1 seconds) for the CT group after 15 days, corresponding to the 7.8% decrease in .VO2max. These findings suggest that in competitive women middle-distance runners, actual performance decrements found after 15 days of CT most likely are due to declines in .VO2max.

This study examined the relationship among resting cortisol levels measured in serum (SER), saliva (SAL). overnight urine (ON) and 24 h urinary free cortisol (24 h) samples to determine which would be most appropriate for monitoring recovery from the physiological stress imposed by exercise training. Eight (3 female, 5 male) physical education students (X+/-SD age= 22+/-2 y, mass= 73.6+/-17.1 kg; predicted 120m shuttle] VO2max = 3.83+/-1.34 L x min(-1); 51.4+/-8.0 mL x kg(-l) x min(-1)) volunteered. Venous blood, saliva and urine were collected following one day of recovery from training. Morning (0730-0800 h) cortisol was analysed commercially using solid phase radioimmunoassay. Mean resting cortisol concentrations for these samples were in the high end of the normal reference interval previously reported for this population in the literature: SER (656.5+/-122.3 nmol x L(-1)). SAL (41.9+/-12.3 nmol x L(-1)), ON (72.0+/-19.5 nmol x L(-1)) and 24 h (170.8 +/-58.7 nmol x day(-1)). Intraclass correlation coefficients (R) showed a high correlation between 24 h versus SER (R=0.99), SAL (R=0.97), and ON (R=0.97) cortisol, and between SER and SAL cortisol (r=0.99) Limits of agreement analysis to determine measurement error also revealed significant correlations (r2=0.60-0.99) between the dependent variables. In conclusion, the strong intraclass correlation coefficient between 24 h cortisol versus SAL and SER suggests that either sample can be used to monitor cortisol hormone during a recovery period from exercise training. The use of SAL samples for cortisol analysis may have many advantages due to its non-invasive nature.

In this study we examined the oxygenation trend of the vastus medialis muscle during sustained high-intensity exercise. Ten cyclists performed an incremental cycle ergometer test to voluntary exhaustion [mean (SD) maximum oxygen uptake 4.29 (0.63) l x min(-1); relative to body mass 60.8 (2.4) ml x kg(-1)min(-1)] and a simulated 20-km time trial (20TT) on a wind-loaded roller system using their own bicycle (group time = 23-31 min) in two separate sessions. Cardiorespiratory responses were monitored using an automated metabolic cart and a wireless heart rate monitor. Tissue absorbency, which was used as an index of muscle oxygenation, was recorded simultaneously from the vastus medialis using near-infrared spectroscopy. Group mean values for oxygen uptake, ventilation, heart rate, respiratory exchange ratio, power output, and rating of perceived exhaustion were significantly (P < or = 0.05) higher during the incremental test compared to the 20TT [4.29 (0.63) l x min(-1) vs 4.01 (0.55) l x min(-1), 120.4 (26) l x min(-1) vs 97.6 (16.1) l x min(-1), 195 (8) beats x min(-1) vs 177 (9) beats min(-1), 1.15 (0.06) vs 0.93 (0.06), 330.1 (31) W vs 307.2 (24.5) W, and 19 (1.5) vs 16 (1.7), respectively]. Oxygen uptake and heart rate during the 20TT corresponded to 93.5% and 90.7%, respectively, of the maximal values observed during the incremental test. Comparison of the muscle oxygenation trends between the two tests indicated a significantly greater degree of deoxygenation during the 20TT [-699 (250) mV vs 439 (273) mV; P < or = 0.05] and a significant delay in the recovery oxygenation from the 20TT. The mismatching of whole-body oxygen uptake and localised tissue oxygenation between the two tests could be due to differences in muscle temperature, pH, localised blood flow and motor unit recruitment patterns between the two tests.

This study compared breathing frequency (fB) during a ventilation threshold (VT) test with fB during a simulated 40 km time trial (40TT) to assess whether fB can be used to monitor exercise intensity. Twenty-six male cyclists (mean +/- SD VO2max = 4.42 +/- 0274 l.min-1) performed an incremental VT ergometer test and a simulated 40TT on a set of wind-loaded rollers. During the 40TT, expired gas was collected for 3 min using open circuit spirometry at 10 km intervals. A significant correlation (r = 0.89; p < or = 0.05) was found between the fB threshold (VTf) and the gas exchange VT (VTg) (3.42 +/- 0.08 and 3.31 +/- 0.09 l.min-1, respectively). No differences were found in VO2 at the VTf vs. X VO2 (3.48 +/- 0.08 l.min-1) during the simulated 40TT. However, when fB in br.min-1 calculated from the VT test (32.5 br.min-1), was compared with fB during the 40TT (45.6 br.min-1), there was a significant difference. Ventilation, heart rate and the respiratory exchange ratio were all significantly higher during the 40TT. Although a significant relationship was found between the VT test and the 40TT for VTf measured in l.min-1 of VO2 (r = 0.66; p < or = 0.05), fB in br.min-1 obtained from the incremental test should not be used to identify exercise training intensity. These data suggest that during competition, trained athletes exercise at a higher fB than that determined when being tested, implying that fB in br.min-1 may not be a valid measurement of exercise intensity.

The influence of tapering on the metabolic and performance parameters in endurance cyclists was investigated. Cyclists (n = 25) trained 5 days.week-1, 60 min.day-1, at 75-85% maximal oxygen consumption (VO2max) for 8 weeks and were then randomly assigned to a taper group: 4D (4 days; n = 7), 8D (8 days; n = 6), CON (control, 4 days rest; n = 6), NOTAPER (non-taper, continued training; n = 6). Muscle biopsy specimens taken before and after training and tapering were analysed for carnitine palmityltransferase (CPT), citrate synthase, beta-hydroxyacyl CoA dehydrogenase (HOAD), cytochrome oxidase (CYTOX), lactate dehydrogenase, glycogen and protein. Significant increases in VO2max (6%), a 60-min endurance cycle test (34.5%), oxidative enzymes (77-178%), glycogen (35%) and protein (34%) occurred following training. After the taper, HOAD and CPT decreased 25% (P less than 0.05) and 26% respectively, in the CON. Post-taper CYTOX values were different (P less than 0.05) for 4D and 8D compared with CON. Muscle glycogen levels were increased (P less than 0.05) after tapering in the 4D, 8D and CON, but decreased in NOTAPER. Similarly, power output at ventilation threshold was significantly increased in the 4D (27.4 W) and 8D (27 W) groups, but decreased (22 W) in the NOTAPER. These findings suggest that tapering elicited a physiological adaptation by altering oxidative enzymes and muscle glycogen levels. Such an adaptation may influence endurance cycling during a laboratory performance test.