Simultaneous Physical and Mental Effort Alters Visual Function

Maximal incremental exercise improves macular photostress recovery time and lowers intraocular pressure in healthy athletes

OBJECTIVES

Better visual performance in athletes compared to non-athletes could suggest improved macular function through physical exertion. The study aimed to investigate the effect of maximal incremental treadmill (MIT) exercise on macular function.

DESIGN

An interventional study comparing the effect of maximal incremental treadmill (MIT) exercise until volitional exhaustion between athletes (n = 26) and non-athletes (n = 26).

METHODS

Participants underwent an ophthalmological assessment involving repeated measurements of the photostress recovery time (PSRT) at baseline and post-exercise. PSRT was recorded after a 10-second exposure of the macular to an intense light source from an ophthalmoscope positioned 2 cm in front of the eye. Secondary outcome measures also recorded included the best-corrected visual acuity (BCVA) and the intraocular pressure (IOP).

RESULTS

Compared to the baseline, MIT exercise markedly improved the PSRT of athletes from 42.7 ± 1.6 s to 39.6 ± 1.4 s (P < 0.001), while having no significant changes in the PSRT of non-athletes. After adjusting for exercise duration, the exercise intervention showed significant effects on the PSRT improvement in the athletes compared to non-athletes after exercise [F(1,49) = 16.941, P < 0.001], with estimated marginal means of 3.00 s and 0.47 s, respectively. Also, the exercise intervention resulted in significant improvements in IOP (P < 0.001) and BCVA (P < 0.01) of both groups.

CONCLUSIONS

MIT exercise improves macular function, BCVA, and reduced IOP in healthy athletes. Maximal incremental exercise may be recommended for competitive sports athletes seeking optimal visual performance, as long as it does not adversely impact other relevant non-visual factors.

Effects of a maximal cycling all-out anaerobic test on visual performance

CLINICAL RELEVANCE

All-out exercise may not impair all central nervous system processes, such as those related to visual-motor abilities, and may actually prove stimulatory to such tasks allowing athletes and sports conditioning specialists to develop strategies to take advantage of/mitigate the effects of such exercise on athletic performance.

BACKGROUND

Despite research indicating that visual-motor abilities play a critical role in athletic performance, research has primarily focused on the effect of all-out exercise on processes along the motor pathway, such as resultant force production or simple cognitive tasks. Such research has neglected to investigate the effect of all-out exercise on visual tasks. When investigations on visual tasks are forthcoming, they focus on prolonged aerobic exercise, which is not the primary metabolic pathway for all, or even the majority of sports.

METHODS

Sixty untrained males (experimental group; N = 30, control group; N = 30) completed a standardised six-item baseline sports vision test battery and one week later, the experimental participants returned to undertake a 30-second Wingate anaerobic test (30-WAnT) immediately followed by the same test battery.

RESULTS

Significant (P < 0.05) improvements were found in accommodation facility, saccadic eye movement, speed of recognition, peripheral awareness and hand-eye coordination (P < 0.001 for all), but not visual memory (P = 0.242) following the 30-WAnT.

CONCLUSIONS

Although the mechanisms underlying these improvements in visual task performance have not yet been studied, this study suggests that simple anaerobic all-out exercise does not cause central- or brain-based fatigue impairing the oculomotor system but may rather provide "excitability" of the underlying motor cortex, motoneurons and/or corticofugal connections utilised in visual task response. It appears that the sweeping improvements in visual task performance elucidate the need for an intense anaerobic warm-up when training visual skills and when visual skills form an integral part of athletic performance.

The effect of high-intensity physical exertion on measures of cervical spine, vestibular/ocular-motor screening, and vestibulo-ocular reflex function in university level collision and combative sport athletes

OBJECTIVES

To examine how high-intensity physical exertion affects clinical measures of cervical spine (CSp), vestibular/ocular motor screen (VOMS), and vestibulo-ocular reflex (VOR) function.

DESIGN

Case series.

SETTING

Sports Medicine Centre.

PARTICIPANTS

A total of 37 athletes consented to participate (22 rugby, 15 wrestling; 9 men, 28 women; median age = 19 years [range 17-23 years]).

MAIN OUTCOME MEASURES

Outcome measures included tests of CSp (cervical flexor endurance, head perturbation test, cervical flexion rotation test and anterolateral strength), VOR (head thrust test and dynamic visual acuity [DVA]), and a quantified version of the VOMS. These metrics were assessed prior to and after completing the 30-15 Intermittent Fitness Test. Bland-Altman plots and Wilcoxon signed-rank tests were utilized to analyze the data using an alpha of p < 0.004.

RESULTS

Cervical anterolateral strength (kg) was reduced post-exertion on the left (z = 3.87; p < 0.001), but not on the right between conditions (z = -1.49; p = 0.14). Athletes reported increased dizziness (z = -3.55; p = 0.004) and had reduced DVA following exertion (z = -2.78; p < 0.001). All other metrics were not significantly different following exertion (p > 0.011).

CONCLUSION

Reduced performance on DVA, decreased left-anterolateral strength, and increased dizziness occurred following high-intensity exertion in varsity collision and combative athletes, which has implications for sideline screening for sport-related concussion.

The impact of high- and moderate-intensity exercise on near-point of convergence metrics

Background: Near point of convergence (NPC) assesses the vergence ability of the visuo-oculomotor system; however, little is known regarding: the extent and duration exercise impacts NPC and the between- and within-day reliability of NPC metrics.Methods: An accommodative ruler with a miniature Snellen chart was placed upon the philtrum (upper lip). Participants (n=9) focused upon a 'V' sized 20/20, while the chart was moved at ~1-2 cm/s toward and away from the eyes (twice in each direction). Testing commenced at 8:00am with NPC measures being collected at baseline before three randomized conditions with serial follow-ups occurring at six post-condition timepoints (0-8 hours following). The conditions consisted of 25-minutes high-intensity intervals (10, one-minute intervals at ~85-90% heart-rate reserve), 45-minutes of moderate-intensity exercise (at ~50-60% heart-rate reserve), and a control condition (30-minutes quiet rest).Results: NPC was not impacted across any of the three conditions (all p > .59). Additionally, NPC measures between baseline conditions and across the control condition displayed very high levels of within-day and between-day reliability (coefficient of variation <3.8%).Conclusions: Future NPC measures using an accommodative ruler can be taken immediately following exercise and may be pertinent as a complementary tool in the future sideline screening of concussion.

Dissociable Effects of Executive Load on Perceived Exertion and Emotional Valence during Submaximal Cycling

Endurance physical exercise is accompanied by subjective perceptions of exertion (reported perceived exertion, RPE), emotional valence, and arousal. These constructs have been hypothesized to serve as the basis for the exerciser to make decisions regarding when to stop, how to regulate pace, and whether or not to exercise again. In dual physical-cognitive tasks, the mental (executive) workload generated by the cognitive task has been shown to influence these perceptions, in ways that could also influence exercise-related decisions. In the present work, we intend to replicate and extend previous findings that manipulating the amount of executive load imposed by a mental task, performed concomitantly with a submaximal cycling session, influenced emotional states but not perceived exertion. Participants (experienced triathletes) were asked to perform a submaximal cycling task in two conditions with different executive demands (a two-back version of the n-back task vs. oddball) but equated in external physical load. Results showed that the higher executive load condition elicited more arousal and less positive valence than the lower load condition. However, both conditions did not differ in RPE. This experimental dissociation suggests that perceived exertion and its emotional correlates are not interchangeable, which opens the possibility that they could play different roles in exercise-related decision-making.

Preliminary evaluation of the VIsion PERformance (VIPER) simulator

BACKGROUND

This study evaluated the VIsion PERformance (VIPER) simulator's ability to assess the functional visual performance in warfighters conducting civilian and military tasks.

METHODS

Thirty service members, aged 25-35 years old with a best corrected distance visual acuity (VA) better than or equal to 20/20 or logarithm of the minimum angle of resolution (logMAR) 0.00, were randomized to locate and identify road signs and mock improvised explosive devices (IEDs) under either daytime conditions or with infrared imagery, with (cc) and without (sc) wearing their habitual correction. Participants also underwent binocular uncorrected (UDVA) and corrected (CDVA) visual assessment, refraction, contrast sensitivity testing and wavefront aberrometry.

RESULTS

The mean age was 28.47 years. The manifest spherical equivalent was - 3.16 ± 1.75 diopters (D), the UDVA in both eyes (OU) was logMAR 0.83 ± 0.47, and the CDVA OU was - 0.11 ± 0.06. For VIPER, the mean difference in the detection distance (DD) for road signs ccDD vs. scDD was 76.7 ± 52.8 m (P < 0.001). The average difference in identification distance (ID) ccID vs. scID was 13.9 ± 6.3 m (P < 0.001). The mean accuracies were 83.5 and 27.9% for cc and sc, respectively (P < 0.001). The regression analysis indicated that a 1.6 m change in the distance accounts for a 1% change in the accuracy (P = 0.002). Without correction, a 4.1 m change accounts for a 1% change in the accuracy (P < 0.001). The average IED ccDD was 29.9 ± 8.2 m, and that for scDD was 13.2 ± 13.6 m (P < 0.001). The average IED ccID was 32.2 ± 6.2 m and that for the scID was 7.4 ± 10.3 m (P < 0.001). The mean IED identification accuracy was 46.7 and 11.4% for cc and sc, respectively (P < 0.001).

CONCLUSIONS

The preliminary results reflect VIPER's ability to assess functional visual performance when detecting and identifying signs and IEDs. Furthermore, VIPER is able to detect performance changes with and without correction.

A test-retest assessment of the effects of mental load on ratings of affect, arousal and perceived exertion during submaximal cycling

This study aimed to test the effects of mental (i.e. executive) load during a dual physical-mental task on ratings of perceived exertion (RPE), affective valence, and arousal. The protocol included two dual tasks with matched physical demands but different executive demands (2-back and oddball), carried out on different days. The procedure was run twice to assess the sensitivity and stability of RPE, valence and arousal across the two trials. Linear mixed-effects analyses showed less positive valence (-0.44 points on average in a 1-9 scale; R_β² = 0.074 [CI90%, 0.052-0.098]), and heightened arousal (+0.13 points on average in a 1-9 scale; R_β² = 0.006 [CI90%, 0.001-0.015]), for the high executive load condition, but showed no effect of mental load on RPE. Separated analyses for the two task trials yielded best-fitting models that were identical across trials for RPE and valence, but not for arousal. Model fitting was improved by assuming a 1-level autoregressive covariance structure for all analyses. In conclusion, executive load during a dual physical-mental task modulates the emotional response to effort, but not RPE. The autoregressive covariance suggests that people tend to anchor estimates on prior ones, which imposes certain limits on scales' usability.