PURPOSE: The purpose of this investigation is to examine the impact of acute aerobic exercise of varying intensities on cue reactivity to alcohol in heavy alcohol users. METHODS: Fourteen participants (6 males, 8 female) (Age = 18-23), completed 3 experimental sessions. Heavy alcohol use was identified using an adapted version of the CAGE questionnaire. During one session subjects rested (REST) for 30 minutes and during the other two sessions subjects exercised for 30 minutes at a moderate or vigorous exercise intensity. Prior to and immediately following each session, EEG data were while subjects were exposed to 210 images (90 alcoholic drinks (ALC), 90 non-alcoholic drinks (NON), 30 control images). Images were presented in a random order and proceeded by a fixation stimulus using a variable time span (0.5 to 1.5 sec). Adaptive mean amplitude for P300 (210-240 ms post stimulus) and late positive potential (LPP) (400-600 ms post stimulus) were calculated in parietal-occipital electrodes. RESULTS: The P300 response to ALC increased from pre to post in both REST (pre = 2.80 ± 0.58 μV, post = 3.65 ± 0.39 μV; p = 0.001) and VIG (pre = 2.82 ± 0.36 μV; post = 3.36 ± 0.43 μV, p = 0.023) conditions. In comparison, the P300 response to ALC decreased in the MOD (pre = 2.93 ± 0.33 μV; post = 1.66 ± 0.0.35 μV, p = 0.002) condition. The LPP to ALC was much greater after REST (Pre = 0.82 ± 0.35 μV, Post = 1.86 ± 0.48 μV; p = 0.001) than after MOD (Pre = 0.87 ± 0.26 μV, Post = -0.07 ± 0.26 μV; p = 0.001) and VIG (Pre = 0.97 ± 0.22 μV, Post = -0.85 ± 0.43 μV; p = 0.01). There was no significant difference in reaction time from pre to post for REST (Pre Rest: 457.84 ± 10.20 msec, Post Rest: 458.84 ± 14.95 msec) with significant difference from pre to post in both MOD (Pre = 472.70 ± 15.36 msec, Post = 434.31 ± 33.96 msec: p = 0.001) and VIG (Pre = 472.70 ± 15.36 msec, Post = 451.42 ± 15.93 msec; p = 0.03). ALC craving was less for MOD (3.6 ± 0.7) and VIG (2.6.1 ± 0.6) compared to REST (6.1 ± 0.7) (p = 0.023). CONCLUSION: These findings suggest that the impact of exercise on cue reactivity to images of alcohol in heavy alcohol users is related to exercise intensity. Specifically, it appears that moderate intensity exercise has a greater benefit than vigorous exercise, while both intensities decrease self-reported cravings.

Mental Fatigue (MF) has been associated with reduced physical performance but the mechanisms underlying this result are unclear. A reduction in excitability of the corticomotor system is a way mental fatigue could negatively impact physical performance. Carbohydrate (CHO) mouth rinse (MR) has been shown to increase corticomotor excitability. PURPOSE: The purpose of this study was to determine if CHO MR impacts corticomotor excitability after MF. METHODS: Fifteen subjects (nine females, six males; age = 23 ± 1 years; height = 171 ± 2 cm; body mass = 69 ± 3 kg; BMI = 23.8 ± 0.7) completed two sessions under different MR conditions (Placebo (PLAC), 6.4% glucose (CHO)) separated by at least 48 h and applied in a double-blinded randomized fashion. Motor-evoked potential (MEP) of the left first dorsal interosseous (FDI) was determined by transcranial magnetic stimulation (TMS) before and after MF. Perceived MF was recorded before and after the MF task using a 100 mm visual analog scale (VAS). RESULTS: MF was greater following PLAC (+30.4 ± 4.0 mm) than CHO (+19.4 ± 3.9 mm) (p = 0.005). MEP was reduced more following PLAC (−16.6 ± 4.4%) than CHO (−3.7 ± 4.7%) (p < 0.001). CONCLUSIONS: CHO MR was successful at attenuating the reduction in corticomotor excitability after MF. Carbohydrate mouth rinse may be a valuable tool at combating the negative consequences of mental fatigue.

Physical exercise has been shown to reduce craving for alcohol in alcoholics. There is a high prevalence of heavy alcohol use in college-aged adults (18-29 years of age). This can be predictive of an alcohol or other substance use disorder developing later in life. Acute exercise alters cue reactivity to addictive substances but it is unknown if the magnitude of change in cue reactivity is impacted by exercise intensity. PURPOSE: The purpose of this investigation is to examine the impact of acute aerobic exercise of varying intensities on cue reactivity to alcohol in heavy alcohol users. METHODS: Nine participants (8 females, 1 male) (Age = 21.5+0.5 years, BMI=23.9+01.1, VO2Max=32.25+1.06 ml.kg-1.min-1) completed 3 experimental sessions. Heavy alcohol use was identified using an adapted version of the CAGE questionnaire. During one session subjects rested (REST) for 30 minutes and during the other two sessions subjects exercised for 30 minutes at a moderate (MOD: 53+7% of Peak HR) or vigorous (VIG: 76+2% of Peak HR) exercise intensity. Sessions were randomized for each participant. Prior to and immediately following each session, EEG data were collected using a 64-channel system while subjects were exposed to 210 images (90 alcoholic drinks (ALC), 90 non-alcoholic drinks (NON), 30 control images). Images were presented in a random order and proceeded by a fixation stimulus using a variable time span (0.5 to 1.5 sec). Adaptive mean amplitude for P300 (210-240 ms post stimulus) and mean amplitude for the late positive potential (LPP) (400-600 ms post stimulus) were calculated in parietal-occipital electrodes. RESULTS: The P300 response to ALC increased from pre to post in both REST (pre=2.69±0.72 μV, post=3.41±0.52 μV; p=0.002) and VIG (pre=1.62±0.40 μV; post=2.95±0.51 μV, p<0.001) conditions. In comparison, the P300 response to ALC decreased in the MOD (pre=1.31±0.29 μV; post=0.66±0.32 μV, p<0.001) condition. The LPP to ALC was much greater after REST (2.55±0.69 μV) than after MOD (-0.10±0.32 μV; p<0.001) and VIG (0.73±0.78 μV; p=0.003). CONCLUSION: These findings suggest that the impact of exercise on cue reactivity to images of alcohol in heavy alcohol users is dependent on exercise intensity. Specifically, it appears that moderate intensity exercise has a greater benefit than vigorous exercise.

PURPOSE: The purpose of this investigation is to determine the effects of different forms of a CHO MR on quadriceps muscle performance and corticospinal motor excitability. METHODS: Ten subjects (5 females, 5 males; 25±1 years; 1.71±0.03 m 73±5 kg) completed 4 trials. A different MR condition was applied during each trial (Placebo (PLA), 6.4% glucose (GLU), 6.4% maltose (MAL), 6.4% maltodextrin (MDX)). Maximal voluntary contraction (MVIC) of the right quadriceps and motor-evoked potential (MEP) of the right rectus femoris was determined pre (10 min), immediately after, and post (10 min) MR. MEP was precipitated by transcranial magnetic stimulation (TMS) during muscle contraction (50% of MVIC). MR was held in the mouth for 20 s and treatments were applied using a Latin square design. The relative change in MEP from pre-measures was different across treatments (p=0.025) but was not different across time (p=0.357). RESULTS: Relative change in MEP was greater for all CHO conditions immediately after (GLU=2.58±5.33%; MAL=3.92±3.90%; MDX=18.28±5.57%) and 10 min after (GLU=14.09±13.96%; MAL=8.64±8.67%; MDX=31.54±12.77%) MR compared to PLA (Immediately after=-2.19±4.25%, 10 min=-13.41±7.46%). The relative change in MVC was greater for CHO conditions immediately (GLU=3.98±2.49%; MAL=5.89±2.29.90%; MDX=7.66±1.93%) and 10 min after (GLU=7.22±2.77%; MAL=10.26±4.22%; MDX=10.18±1.50%) MR compared to PLA (Immediately after=-3.24±1.50%, 10 min=-6.46±2.22%). CONCLUSIONS: CHO MR increased corticospinal motor excitability and quadriceps muscle performance immediately and 10 min after application; however, the form of CHO used did not influence this response.

Physical exercise has been shown to reduce craving for alcohol in alcoholics. There is a high prevalence of heavy episodic drinking in college-aged adults (18-29 years of age). This can be predictive of an alcohol or other substance use disorder developing later in life. PURPOSE: The purpose of this investigation is to examine the impact of acute aerobic exercise on cue reactivity to alcohol in heavy episodic drinkers. METHODS: Seven participants (6 females, 1 male) (Age = 20+0.44 years, BMI=22.6+0.59, VO2Max=32.014+2.14 ml.kg-1.min-1) completed 2 experimental sessions. Heavy episodic drinking was identified using an adapted version of the CAGE questionnaire. During one session subjects rested for 30 minutes and during the other session subjects exercised for 30 minutes at a moderate exercise intensity (77+1% of Peak HR). Sessions were randomized for each participant. Prior to and immediately following each session, EEG data were collected using a 64-channel system while subjects were exposed to 180 images (90 alcoholic drinks (ALC), 90 non-alcoholic drinks (NON)). Images were presented in a random order and proceeded by a fixation stimulus using a variable time span (0.5 to 1.5 sec). Mean amplitude and peak latency was calculated for P300 (300-380 ms post stimulus) in parietal-occipital electrodes. RESULTS: Before exercise, subjects had a greater response (p=0.002) to ALC (1.85±0.20 μV) as compared to NON (1.47±0.21 μV). After exercise the response to ALC (1.62±0.37 μV) was similar to that seen for NON (1.72±0.31 μV). Before exercise the peak latency was shorter (p=0.025) for ALC (325±32 ms) compared to NON (366±25 ms). After exercise, the peak latency was similar for ALC (313±26 ms) and NON (323±27 ms). CONCLUSION: These findings suggest that acute aerobic exercise of moderate intensity attenuates cue reactivity to images of alcoholic beverages in heavy episodic drinkers.

Application of a carbohydrate (CHO) mouth rinse (MR) prior to exercise has been shown to improve physical performance and facilitate corticospinal motor excitability. It is unclear if different forms of CHO impact this phenomenon. PURPOSE: The purpose of this investigation is to determine the effects of different forms of a CHO MR on muscular performance and corticospinal motor excitability. METHODS: Ten normal healthy subjects (5 females, 5 males; 25±1 years; 1.71±0.03 m 73±5 kg) completed 4 trials each separated by at least 48 hours. A different MR condition was applied during each trial (Placebo (PLAC), 6.4% glucose (GLU), 6.4% maltose (MAL), 6.4% maltodextrin (MDX)). Maximal voluntary contraction (MVC) of the right knee extensors and motor-evoked potential (MEP) of the right vastus medialis was determined pre (10 min before), immediately after, and post (10 min after) application of the MR. MEP was precipitated by applying transcranial magnetic stimulation (TMS) during muscle contraction (50% of MVC). The MR was held in the mouth for 20 sec and MR treatments were applied using a Latin square design. RESULTS: No differences were found in the change of MEP from pre to immediately after the MW across the conditions (PLAC=1.5±4.4%; GLU=-6.2±11.2%; MAL=3.9±3.4%; MDX=8.9±7.9%). In contrast, the increase in MEP was greater at the post time point in CHO conditions (GLU=-11.3±14.7%, p=0.01; MAL=12.9±7.9%, p=0.07; MDX=28.0±14.4%, p=0.02) as compared to PLAC (PLAC=-14.3±7.8%). MVC was similar at pre (PLAC=260±26 Nm; GLU=241±19 Nm MAL=245±21 Nm; MDX=248±25 Nm), after (PLAC=269±26 Nm; GLU=249±18 Nm MAL=257±19 Nm; MDX=250±23 Nm), and 10 min after (PLAC=262±28 Nm; GLU=256±17 Nm MAL=269±25 Nm; MDX=253±21 Nm) the MW. CONCLUSIONS: CHO MR increased corticospinal motor excitability 10 min after application; however, the form of CHO used did not influence this response. The increase in corticospinal motor excitability did not translate into an improvement in motor performance.

Acute exercise has been shown to have a hypoanalgesic effect, reducing the sensation of pain. It is unclear if exercise modifies sensory perception below the pain threshold. PURPOSE: The purpose of this experiment is to examine the effects of acute exercise on tactile sensory perception during and after acute exercise. METHODS: Eight subjects (5 males, 3 females; Age=25±1 years; Height=1.72±0.02 m; Weight=75.0±3.7 kg; VO2max=40.3±2.7 ml.kg-1.min-1) completed 3 experimental sessions. During the first two sessions subjects either rested for 20 minutes or completed a maximal exercise test on a Lode semi-recumbent Corival cycle ergometer. The order of these two treatments was assigned in a randomized-counterbalanced fashion. Immediately before and 5 minutes after the maximal exercise test, tactile sensation was assessed using a Cortical Metrics (CM-1) portable vibrotactile stimulator. During the test sensation was assessed on the tip of the 2nd and 3rd digits of the non-dominant hand using a blunt stimulus probe. During the tactile sensation test subjects were evaluated for simple reaction time (RT), amplitude discrimination without (AMP) and with (AMPadapt) a conditioning stimulus, and temporal order judgment without (TOJ) and with (TOJadapt) a conditioning stimulus. The last experimental session required subjects to cycle at 70% of ventilatory threshold for 60 minutes (SubmaxEx). Tactile sensation was assessed before, after 10 minutes of exercise, after 50 minutes of exercise, and 5 minutes after completion of exercise. RESULTS: Tactile sensation was not changed as a result of the maximal exercise test. RT, TOJ, and TOJadapt were also not changed as a result ofSubmaxEx. Difference limen decreased in AMP (Pre=48.6±8.5 µm; 10 min=30.8±7.0 µm; 50 min=45.7±10.2 µm; Post=28.7±5.7 µm) (p=0.04) and increased in AMPadapt (Pre=36.1±5.6 µm; 10 min=55.4±18.1 µm; 50 min=66.3±12.0 µm; Post=85.7±12.1 µm) (p=0.01) as a consequence of SubmaxEx. CONCLUSIONS: The results of this investigation indicate that tactile sensation is altered during and as a result of submaximal exercise. Specifically, these data suggest that adaptability of the somatosensory system is altered during and after submaximal exercise.

Concussions are occurring at alarming rates in the United States and have become a serious public health concern. The CDC estimates that 1.6 to 3.8 million concussions occur in sports and recreational activities annually. Concussion as defined by the 2013 Concussion Consensus Statement "may be caused either by a direct blow to the head, face, neck or elsewhere on the body with an 'impulsive' force transmitted to the head." Concussions leave the individual with both short- and long-term effects. The short-term effects of sport related concussions may include changes in playing ability, confusion, memory disturbance, the loss of consciousness, slowing of reaction time, loss of coordination, headaches, dizziness, vomiting, changes in sleep patterns and mood changes. These symptoms typically resolve in a matter of days. However, while some individuals recover from a single concussion rather quickly, many experience lingering effects that can last for weeks or months. The factors related to concussion susceptibility and the subsequent recovery times are not well known or understood at this time. Several factors have been suggested and they include the individual's concussion history, the severity of the initial injury, history of migraines, history of learning disabilities, history of psychiatric comorbidities, and possibly, genetic factors. Many studies have individually investigated certain factors both the short-term and long-term effects of concussions, recovery time course, susceptibility and recovery. What has not been clearly established is an effective multifaceted approach to concussion evaluation that would yield valuable information related to the etiology, functional changes, and recovery. The purpose of this manuscript is to show one such multifaceted approached which examines concussions using computerized neurocognitive testing, event related potentials, somatosensory perceptual responses, balance assessment, gait assessment and genetic testing.

The primary somatosensory cortex shows precise topographical organisation, but can be quickly modified by alterations to sensory inputs. Temporally correlated sensory inputs to the digits can result in the merging of digit representations on the cortical surface. Underlying mechanisms driving these changes are unclear but the strengthening of intra-cortical synaptic connections via Hebbian mechanisms has been suggested. We use fMRI measures of temporal coherence to infer alterations in the relative strength of neuronal connections between digit regions 2 and 4 following 3 hours of synchronous and asynchronous co-activation. Following synchronous co-activation we find a 20% increase in temporal coherence of the fMRI signal (p=0.0004). No significant change is seen following asynchronous co-activation suggesting that temporal coincidence between the two digit inputs during co-activation is driving this coherence change. In line with previous work we also find a trend towards reduced separation of the digit representations following synchronous co-activation and significantly increased separation for the asynchronous case. Increased coherence is significantly correlated with reduced digit separation for the synchronous case. This study shows that passive synchronous stimulation to the digits strengthens the underlying cortical connections between the digit regions in only a few hours, and that this mechanism may be related to topographical re-organisation.

Student-athletes, specifically in sports such as soccer and football, have a high risk of concussions because of the high amount of contact. PURPOSE: This research project investigated the influence of concussion history on cognitive function in student-athletes. METHODS: One hundred student-athletes from football (n = 59), men's soccer (n = 23) and women's soccer (n = 18) participated in the study. Each participant completed the Immediate Post-Concussion Assessment Cognitive Testing (ImPACTTM). Additionally, EEG was recorded to determine event related potentials (ERPs) during the Eriksen Flanker Task and an auditory oddball task. RESULTS: The ImPACTTM found that verbal memory was worse in those who have previously had a concussion versus those with no history (p = 0.013). The Flanker Task yielded significant differences for percent correct in congruent trials (p = 0.033). Evidence was found that the P3 ERP component was influenced by concussion history with those suffering from a previous concussion to have larger latency at site Pz for the incongruent trials of the Flanker Task (p = 0.038). The auditory oddball task provided additional evidence in greater P3 amplitude for those with a concussion history at size Pz (p = 0.007). Nonsignificant trends were found at FCz (p = 0.10). Both latency and amplitude are thought to represent decrements in cognitive processing of stimuli. CONCLUSIONS: The present study found concussion history to have an influence in cognitive processing in student-athletes. These decrements in processing can have an influence on quality of life in those with a concussion and needs to be explored more.

Individuals with temporomandibular disorder (TMD) suffer from persistent facial pain and exhibit abnormal sensitivity to tactile stimulation To better understand the pathophysiological mechanisms underlying TMD we investigated cortical correlates of this abnormal sensitivity to touch Using functional magnetic resonance imaging (fMRI) we recorded cortical responses evoked by low frequency vibration of the index finger in subjects with TMD and in healthy controls (HC) Distinct subregions of contralateral primary somatosensory cortex (SI) secondary somatosensory cortex (511) and insular cortex responded maximally for each group Although the stimulus was inaudible primary auditory cortex was activated in TMDs TMDs also showed greater activation bilaterally in anterior cingulate cortex and contralaterally in the amygdala Differences between TMDs and HCs in responses evoked by innocuous vibrotactile stimulation within SI 511 and the insula paralleled previously reported differences in responses evoked by noxious and innocuous stimulation respectively in healthy individuals This unexpected result may reflect a disruption of the normal balance between central resources dedicated to processing innocuous and noxious input manifesting itself as increased readiness of the pain matrix for activation by even innocuous input Activation of the amygdala in our TMD group could reflect the establishment of aversive associations with tactile stimulation due to the persistence of pain Perspective This article presents evidence that central processing of innocuous tactile stimulation is abnormal in TMD Understanding the complexity of sensory disruption in chronic pain could lead to improved methods for assessing cerebral cortical function in these patients (C) 2010 by the American Pain Society

Previous studies have shown changes in brain activity as a result of exercise; however, few studies have examined changes during exercise. The purpose of this study was to examine brain activity during a graded exercise test. Twenty male participants performed a graded exercise test on a recumbent cycle ergometer. Exercise intensity was set initially at 50W and was increased by 50W every 2 minutes until volitional fatigue was reached. Electroencephalography (EEG) was measured prior to the onset of exercise, during the last minute of each stage of exercise, immediately post-exercise, and 10 minutes into recovery. EEG was recorded from 8 scalp sites leading to analysis of alpha 1, alpha 2, beta 1, beta 2, and theta activities. Expired air was collected and analyzed for ventilation rate (VE), VO2, % of peak VO2, and Respiratory Exchange Ratio (RER). No differences were seen in EEG between the hemispheres of the brain. There was, however, a significant increase in brain activity across the spectrum occurring at 200 W through immediately post-exercise. Brain activity returned to pre- exercise levels by 10 minutes post. VO2, % of peak VO2 and RER increased linearly with exercise intensity. VE increased linearly through 200 W; however, a disproportionate increase was seen in VE from 200 W to peak exercise. The results of this investigation demonstrate that brain activity may be related to exercise intensity. Future research will want to examine how these changes in brain activity influence affective, perceptual and cognitive changes often associated with exercise. Efforts will also need to be made to determine if changes in brain activity during exercise are mediated by central (within the brain) or peripheral mechanisms. Key pointsEEG can be recorded during exercise.Brain EEG activity increases during exercise and may be related to exercise intensity.Brain EEG activity returns to resting levels quickly after the cessation of exercise.

Although sensory problems, including unusual tactile sensitivity, are heavily associated with autism, there is a dearth of rigorous psychophysical research. We compared tactile sensation in adults with autism to controls on the palm and forearm, the latter innervated by low-threshold unmyelinated afferents subserving a social/affiliative submodality of somatosensation. At both sites, the groups displayed similar thresholds for detecting light touch and innocuous sensations of warmth and cool, and provided similar hedonic ratings of the pleasantness of textures. In contrast, increased sensitivity to vibration was seen in the autism group on the forearm, along with increased sensitivity to thermal pain at both sites. These findings suggest normal perception along with certain areas of enhanced perception in autism, consistent with previous studies.

BACKGROUND:Previous reports have demonstrated that short durations of vibrotactile stimuli (less than or equal to 2 sec) effectively and consistently modify both the perceptual response in humans as well as the neurophysiological response in somatosensory cortex. The change in cortical response with adaptation has been well established by a number of studies, and other reports have extended those findings in determining that both GABA- and NMDAR-mediated neurotransmission play a significant role in the dynamic response of somatosensory cortical neurons. In this study, we evaluated the impact that dextromethorphan (DXM), an NMDAR antagonist, had on two distinct vibrotactile adaptation tasks.RESULTS:All subjects, both those that ingested 60 mg DXM and those that ingested placebo, were evaluated for their amplitude discriminative capacity between two simultaneously delivered vibrotactile stimuli both with and without 3 conditions of pre-exposure to adapting stimulation. The results demonstrated that the perceptual metrics of subjects who ingested 60 mg DXM were significantly altered from that of controls when the amplitude discrimination task followed one of the conditions of adapting stimulation. Without the condition of pre-exposure to an adapting stimulus (or stimuli), there was little difference between the observations obtained from the subjects that ingested DXM and controls. Peak impact on subject response occurred at 60 min post-ingestion, whereas the scores of controls who ingested placebo were not impacted.CONCLUSION:The results - that DXM blocks vibrotactile adaptation - is consistent with the suggestion that NMDAR-mediated neurotransmission plays a significant role in the perceptual adaptive response. This finding is also consistent with neurophysiological findings that report observations of the effects of NMDAR block on the SI cortical response to repetitive vibrotactile stimulation.

Few studies have systematically examined changes in brain electrical activity during an acute bout of exercise. Those that have studied changes during exercise have often found an increase in power in the alpha and beta frequency. PURPOSE: To investigate whether the increases in brain activity occur because of an increase in exercise intensity or an accumulation due to the duration of the exercise. METHODS: 30 males (Age = 22.5 ± 3.5 years; Height = 181.1 ± 7.2 cm; Weight = 83.7 ± 17.8 kg) participated in the study. Participants cycled on a recumbent cycle ergometer for 5, 5 min stages for a total of 25 min. The first stage was 50 W; the next 4 stages were randomly assigned at 50W, 100W, 150W or 200W. Brain activity was recorded via EEG (24 lead, PS YLAB EEG System, Contact Precision Instruments, Cambridge, MA) pre-exercise, at the end of each stage of exercise, immediate post exercise (IPE), and 10 min post-exercise. EEG signals were visually inspected for artifact and underwent a Fast Fourier Transform to determine power at the alpha 1 (8.00–10.49 Hz), alpha 2 (10.50–12.99), beta 1 (13.00–17.99 Hz), and beta 2 (18.00–30.00) frequency bands. RESULTS: ANOVA analyses revealed a significant effect for intensity (p <.001) for all EEG frequencies, alpha 1, alpha 2, beta 1 and beta 2. Compared to baseline levels, EEG power for the frequencies increased as exercise intensity increased and returned back to near baseline levels at 10-min post exercise. When running analyses based on the different stages, regardless of intensity, an effect for stage (p <.001) was also seen when compared to baseline levels with increased EEG power during the exercise session. CONCLUSIONS: It appears that the increase in alpha and beta power during exercise may be due to both an accumulation of duration as well as intensity. Future studies should continue to examine the influence of intensity and duration on changes in brain activity. These changes may be important in explaining perceptual, affective and cognitive responses to exercise.