Noll Physiological Research Center, Pennsylvania State University, University Park, Pennsylvania 16802
This mini-review focuses on the effects of aging on human temperature regulation. Although ...comprehensive reviews have been published on this topic (Kenney WL. Exercise and Sport Sciences Reviews , Baltimore: Williams & Wilkins, 1997, p. 41-76; Pandolf KB. Exp Aging Res 17: 189-204, 1991; Van Someren EJ, Raymann RJ, Scherder EJ, Daanen HA, and Swaab DF. Ageing Res Rev 1: 721-778, 2002; and Young AJ. Exp Aging Res 17: 205-213, 1991), this mini-review concisely summarizes the present state of knowledge about human temperature regulation and aging in thermoneutral conditions, as well as during hypo- and hyperthermic challenges. First, we discuss age-related effects on baseline body core temperature and phasing rhythms of the circadian temperature cycle. We then examine the altered physiological responses to cold stress that result from aging, including attenuated peripheral vasoconstriction and reduced cold-induced metabolic heat production. Finally, we present the age-related changes in sweating and cardiovascular function associated with heat stress. Although epidemiological evidence of increased mortality among older adults from hypo- and hyperthermia exists, this outcome does not reflect an inability to thermoregulate with advanced age. In fact, studies that have attempted to separate the effects of chronological age from concurrent factors, such as fitness level, body composition, and the effects of chronic disease, have shown that thermal tolerance appears to be minimally compromised by age.
heat stress; cold stress; thermoregulation; sweating; skin blood flow
Address for reprint requests and other correspondence: W. Larry Kenney, 102 Noll Laboratory, Pennsylvania State University, University Park, PA 16802-6900 (E-mail: w7k{at}psu.edu ).
The LIMBIC Military and Tactical Athletic Research Study (MATARS) framework was established to confirm and extend understanding of concussion with initial studies driven by clinical data collected ...between 2015 and 2020 in a collegiate sports setting. The LIMBIC MATARS framework will be leveraged to apply gold-standard and innovative research designs to advance the science of concussion. This manuscript provides the background, methodology, and initial demographic data associated with the LIMBIC MATARS.
Consensus-based common data elements were used to conduct a retrospective chart review, specific to collegiate athletes diagnosed with concussions between 2015 and 2020 at 11 universities.
A final sample of 1,311 (47.8% female) concussions were diagnosed during the five-year study period from athletes participating in a variety of National Collegiate Athlete Association (NCAA) sports. The LIMBIC MATARS demographic data, align with the NCAA and other pioneering multi-site concussion-related studies in terms of biological sex, race and ethnicity, and sport participation.
This pragmatic, methodological approach was used to address several a priori hypotheses related to concussion, align with other multi-site studies of concussion, and establish a consortium for future investigations.
OBJECTIVETo determine if there were concussion diagnosis and recovery disparities between collegiate athletes with Black and White racial identities. DESIGNRetrospective cohort study. ...METHODSConcussion information was extracted from NCAA athlete medical files at LIMBIC MATARS member institutions from the 2015-16' to 2019-20' academic years. A total of 410 concussions from 9 institutions were included that provided all independent (i.e. racial identity of Black or White) and dependent variable information (i.e. dates of injury, diagnosis, symptom resolution, and return to sport) that were analyzed using Mann-Whitney U tests. The sample consisted of 114 (27.8%) concussions sustained by Black athletes and 296 (72.1%) sustained by White athletes. RESULTSThe overall sample had a median of 0 days between injury occurrence to diagnosis, 7 days to symptom resolution, and 12 days to return to sport. No significant timing differences were observed for concussion diagnosis (p = .14), symptom resolution (p = .39), or return to sport (p = 0.58) between collegiate athletes with Black versus White racial identities. CONCLUSIONSThese findings may reflect equitable access to onsite sports medicine healthcare resources that facilitate concussion management in the collegiate sport setting. Future work should explore these associations with a larger and more diverse sample of collegiate athletes.
This study compared the voluntary fluid intake behavior of older men and women (54-70 yr) when provided cold, palatable beverages and ample opportunity to drink between repeated bouts of exercise in ...the heat.
Thirteen men and 14 women performed four bouts of 15-min cycling at 65% VO2peak followed by 15 min of rest at 30 degrees C and 50% relative humidity. In separate trials, subjects drank either a carbohydrate-electrolyte solution (CES) or water ad libitum during the rest periods and were unaware that their fluid intake was being measured.
Fluid intake behavior was repeatable (intraclass correlation coefficient = 0.75), and subjects drank enough of either beverage to match sweating rates and maintain their body mass (BM). Fluid intake per kilogram of BM was greater with CES (18.7 +/- 2.2 vs 15.1 +/- 2.1 mL x kg(-1); P < 0.05), and plasma volume (PV) was better maintained during the CES trials (-1.3 +/- 1.1 vs -4.2 +/- 1.1% during the second half of the session). Women drank significantly more water than the men on a per kilogram basis (17.2 +/- 2.9 vs 12.8 +/- 1.7 mL x kg(-1) BM), and one woman (BM = 45.7 kg) became hyponatremic (S(NA) = 126 mmol x L(-1)) with symptoms during the water trial.
Older adults drank enough to maintain fluid balance when palatable fluid was readily available; however, CES promoted greater voluntary fluid intake and restored PV losses faster than water. In addition, older women drank more water than men during interval exercise in the heat, which may put smaller women at an increased risk for developing hyponatremia.
Abstract
Purpose
We compared objective brain vital sign metrics derived from event-related potentials (ERPs) of mixed martial arts (MMA) athletes and matched control participants.
Methods
We recorded ...101 successful EEG scans from 12 MMA athletes (24.8 ± 2.6 yr) and 18 matched control participants (26.5±3.5 yr). For this analysis, only “baseline” scans were considered (n=30). “Baseline” was at least 90 days from a previous fight and 90 days (MMA) or 1 year (control) following medical clearance from a previously diagnosed concussion. We derived objective, clinical metrics (brain vital signs) from ERPs for auditory sensation (N100), basic attention (P300), and cognitive processing (N400) evoked while participants listen to a 6-minute auditory stimulus sequence. EEG data were processed using standard methods. N100, P300, and N400 amplitudes and latencies were manually identified on evoked potential waveforms by a blinded reviewer. Differences between groups at the waveform level were evaluated with a mass-univariate analysis using non-parametric resampling. Brain vital signs were compared across groups with a Kruskal-Wallis H-test for independent samples, with FDR correction for multiple comparisons.
Results
Mass-univariate waveform analyses showed significant differences (P < 0.05) between MMA athletes and controls in both P300 and N400 ERPs. The Kruskal-Wallis test identified a significant difference in N400 amplitude (H=7.04, P=.008, Padj=.047) between MMA athletes and controls.
Conclusions
MMA athletes demonstrate significant differences in “baseline” brain vital signs compared to controls, indicating that exposure to repetitive head impacts in MMA may be associated with subconcussive changes in brain function.
Youth football: heat stress and injury risk Bergeron, Michael F; McKeag, Douglas B; Casa, Douglas J ...
Medicine and science in sports and exercise
37, Številka:
8
Journal Article
Local skin blood flow (SkBF) responses can be modified by vasoactive neurotransmitters released from sensory nerves, notably, capsaicin-sensitive primary afferents (CSPAs). Age-specific CSPA function ...was examined in this study by assessing the SkBF response to acute capsaicin (CPZ). Eight young (18–30 years), 8 middle-aged (40–55 years), and 9 older (65–80 years) healthy men participated in the study. Treatment patches of varying CPZ concentration (ethanol and 0.001%–10.0% CPZ) were applied to sites on the ventral forearm. SkBF was measured with a laser Doppler imager. There were significant (p <.001) age-specific differences in the SkBF response to CPZ. In the older group, SkBF was reduced at least 2-fold at all concentrations of CPZ compared with the younger group. The middle-aged group showed an intermediate response. SkBF was significantly elevated above that obtained with a vehicle solution when sites were treated with CPZ concentrations ≥0.1% in middle-aged and younger skin, whereas a significant elevation in SkBF was only achieved with 10% CPZ in older skin. The elevated SkBF in the young and middle-aged groups at higher concentrations of CPZ was the result of both an increased area of vasodilation and an increased magnitude of vasodilation within the vasodilated areas. In the older group, the increase in cutaneous vascular conductance at the highest concentration of CPZ was entirely the result of an increased area of vasodilation. These results suggest impaired CSPA function in aged skin and age-specific differences in the ability of sensory nerves to modify local inflammatory SkBF responses.
Noll Physiological Research Center, The Pennsylvania State University,
University Park, Pennsylvania 16802-6900
Submitted 9 October 2002
; accepted in final form 28 April 2003
Age-related changes in ...neurogenic vasodilation mediated by sensory nerves
may alter local skin blood flow (SkBF) responses in older individuals. The
purpose of this study was to determine the age-specific modification of
cutaneous vasodilation by capsaicin-sensitive primary afferent (CSPA) nerves
during local heating. Nine young (18-30 yr), eight middle-aged (40-55 yr), and
eight older (65-80 yr) healthy men participated in the experiments. Two
local-heating protocols (rapid and slow) were performed before and after 1 wk
of capsaicin pretreatment (CP), used to desensitize CSPAs. All temperatures
were below those that elicit pain. SkBF was measured with a laser-Doppler
imager and indexed to percentage of maximal cutaneous vascular conductance
(%CVC max ). CP caused a significant reduction in %CVC max
in the middle-aged and older groups during slow heating ( P <
0.05), without affecting %CVC max in the young group. During rapid
heating, CP significantly reduced (53.9 ± 4.4 vs. 74.4 ± 7.4%
CVC max , P < 0.05), but did not abolish, the initial
sensory nerve-mediated rise in SkBF in the young group. No significant effects
of CP on SkBF were observed during rapid heating in the middle-aged or older
groups. These results indicate that, with advanced age, CSPA activity is more
important to the maximal SkBF response during prolonged local heating, whereas
it has a reduced role in the initial SkBF peak elicited by rapid local
heating. In summary, CSPA activity contributes modestly to the overall SkBF
response to local heating in an age-specific manner.
skin blood flow; aging; laser-Doppler imaging
Address for reprint requests and other correspondence: T. A. Munce, 229 Noll
Laboratory, University Park, PA 16802-6900 (E-mail:
tam275{at}psu.edu ).
We compared energy flow to the fish community in two contrasting streams in northwest Iowa. Analysis focused on creek chubs (Semotilus atromaculatus) collected from an open prairie stream (Anderson ...Creek) and a forested stream (School Creek). Creek chubs from the prairie stream had significantly higher growth rates than fish from the forested stream. Mean weights for age 0+ fish increased from 7.4g in the forested stream to 10.3g in the prairie stream. Mean weights for age 1+ fish increased from 12.5g to 22.3g. By contrast, age 2+ fish were comparable in size in the two streams. These results are consistent with the well-known river continuum concept which predicts increased energy flow to food webs in open-canopied streams due to increased in-stream primary (autochthonous) production resulting from higher light availability compared to heavily-shaded forested streams which rely more on detritus-based (allochthonous) energy sources from the watershed. We attempted to trace shifts in food sources to food webs of the study streams using stable isotopes, however the results were mixed. The delta super(15)N values for creek chubs from the prairie stream were significantly higher than from the forested stream, although the magnitude of the increase was small (0.5 ppt). There was no difference in delta super(13)C values in fish from the two streams.
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