Visual feedback and declines in attention are associated with altered visual strategy during a force-steadiness task in older adults.

Greater heterogeneity exists in older adults relative to young adults when performing highly skilled manual tasks. The purpose of this study was to assess the influence of visual feedback and attentional demand on visual strategy during a submaximal force-steadiness task in young and older adults. Eye movements of 21 young (age 20-38 yr; 11 females, 10 males) and 21 older (age 65-90 yr; 11 females, 10 males) adults were recorded during a pinch force-steadiness task while viewing feedback with higher and lower gain and while performing a visuospatial task. For the visuospatial task, participants imagined a star moving around four boxes and reported the final location after a series of directions. Performance on standardized tests of attention was measured. All participants gazed near the target line and made left-to-right saccadic eye movements during the force-steadiness tasks without the visuospatial task. Older adults made fewer saccades than young adults (21.0 ± 2.9 and 23.6 ± 4.4 saccades, respectively) and with higher versus lower gain (20.9 ± 4.0 and 23.7 ± 3.5 saccades, respectively). Most participants used the same visual strategy when performing the visuospatial task though seven older adults used an altered strategy; gaze did not stay near the target line nor travel exclusively left to right. Performance on standardized measures of attention was impaired in this subset compared with older adults who did not use the altered visual strategy. Results indicate that visual feedback influences visual strategy and reveals unique eye movements in some older adults when allocating attention across tasks.NEW & NOTEWORTHY This study contributes novel findings of age-related changes in visual strategy and associations with attentional deficits during hand motor tasks. Older adults used fewer saccades than young adults and with higher versus lower gain visual feedback during a force-steadiness task. A subset of older adults used an altered visual strategy when allocating attention across multiple tasks. Given that this subset demonstrated attentional deficits, the altered visual strategy could serve to indicate motor and/or cognitive impairments.

The role of eye movements, attention, and hand movements on age-related differences in pegboard tests.

Well-documented manual dexterity impairments in older adults may critically depend on the processing of visual information. The purpose of this study was to determine age-related changes in eye and hand movements during commonly used pegboard tests and the association with manual dexterity impairments in older adults. The relationship between attentional deficits and manual dexterity was also assessed. Eye movements and hand kinematics of 20 young (20-38 yr) and 20 older (65-85 yr) adults were recorded during 9-Hole Pegboard, Grooved Pegboard, and a visuospatial dual test. Results were compared with standardized tests of attention (The Test of Everyday Attention and Trail Making Test) that assess visual selective attention, sustained attention, attentional switching, and divided attention. Hand movement variability was 34% greater in older versus young adults when placing the pegs into the pegboard and this was associated with decreased pegboard performance, providing further evidence that increased movement variability plays a role in dexterity impairments in older adults. Older adults made more corrective saccades and spent less time gazing at the pegboard than young adults, suggesting altered visual strategies in older compared with young adults. The relationship between pegboard completion time and Trail Making Test B demonstrates an association between attentional deficits and age-related pegboard impairments. Results contribute novel findings of age-associated changes in eye movements during a commonly used manual dexterity task and offer insight into potential mechanisms underlying hand motor impairments in older adults.NEW & NOTEWORTHY This eye tracking study contributes novel findings of age-associated changes in eye movements during the commonly used pegboard tests of manual dexterity, including a greater number of corrective saccades and lesser time gazing at the pegboard holes in older compared with young adults. An association between attentional deficits and dexterity impairments in older adults is also highlighted. Results shed light on potential mechanisms underlying well-documented motor deficits in older adults.

Altered visual strategies and attention are related to increased force fluctuations during a pinch grip task in older adults.

The purpose of the study was to determine the visual strategies used by older adults during a pinch grip task and to assess the relations between visual strategy, deficits in attention, and increased force fluctuations in older adults. Eye movements of 23 older adults (>65 yr) were monitored during a low-force pinch grip task while subjects viewed three common visual feedback displays. Performance on the Grooved Pegboard test and an attention task (which required no concurrent hand movements) was also measured. Visual strategies varied across subjects and depended on the type of visual feedback provided to the subjects. First, while viewing a high-gain compensatory feedback display (horizontal bar moving up and down with force), 9 of 23 older subjects adopted a strategy of performing saccades during the task, which resulted in 2.5 times greater force fluctuations in those that exhibited saccades compared with those who maintained fixation near the target line. Second, during pursuit feedback displays (force trace moving left to right across screen and up and down with force), all subjects exhibited multiple saccades, and increased force fluctuations were associated (rs = 0.6; P = 0.002) with fewer saccades during the pursuit task. Also, decreased low-frequency (<4 Hz) force fluctuations and Grooved Pegboard times were significantly related (P = 0.033 and P = 0.005, respectively) with higher (i.e., better) attention z scores. Comparison of these results with our previously published results in young subjects indicates that saccadic eye movements and attention are related to force control in older adults.NEW & NOTEWORTHY The significant contributions of the study are the addition of eye movement data and an attention task to explain differences in hand motor control across different visual displays in older adults. Older participants used different visual strategies across varying feedback displays, and saccadic eye movements were related with motor performance. In addition, those older individuals with deficits in attention had impaired motor performance on two different hand motor control tasks, including the Grooved Pegboard test.

Are neuronal mechanisms of attention universal across human sensory and motor brain maps?

One's experience of shifting attention from the color to the smell to the act of picking a flower seems like a unitary process applied, at will, to one modality after another. Yet, the unique and separable experiences of sight versus smell versus movement might suggest that the neural mechanisms of attention have been separately optimized to employ each modality to its greatest advantage. Moreover, addressing the issue of universality can be particularly difficult due to a paucity of existing cross-modal comparisons and a dearth of neurophysiological methods that can be applied equally well across disparate modalities. Here we outline some of the conceptual and methodological issues related to this problem and present an instructive example of an experimental approach that can be applied widely throughout the human brain to permit detailed, quantitative comparison of attentional mechanisms across modalities. The ultimate goal is to spur efforts across disciplines to provide a large and varied database of empirical observations that will either support the notion of a universal neural substrate for attention or more clearly identify the degree to which attentional mechanisms are specialized for each modality.

Pain Is Modulated Differently Between Females with and without Patellofemoral Pain: Factors Related to Sensitization.

CONTEXT: Patellofemoral pain (PFP) has poor long-term recovery outcomes. Central sensitization describes central nervous system changes altering pain modulation, which can complicate recovery (poorer prognosis, worse function). Signs of central sensitization include amplified pain facilitation, pain hypersensitivity, and impaired pain inhibition, which can be measured with temporal summation of pain (TSP), pressure pain thresholds (PPTs) and conditioned pain modulation (CPM), respectively. Sex differences exist for these test responses, but female-only PFP investigations of sensitization are uncommon. Understanding pain modulation in females with PFP could improve treatment protocols. OBJECTIVE: To determine whether females with PFP exhibit signs of central sensitization (greater TSP, lower PPTs, reduced CPM) compared to pain-free females. DESIGN: Cross-sectional Setting: Laboratory Patients or Other Participants: Thirty-three females [(20 PFP, 13 pain-free); Age: PFP 29.2 ± 7 years, pain-free 28 ± 7 years; Height: PFP 166.7 ± 5.9cm, pain-free 166 ± 9.5cm, Mass: PFP 66.7 ± 9.6kg, pain-free 69.3 ± 7.5kg). MAIN OUTCOME MEASURES: TSP was assessed with ten punctate stimuli applied to the knee and calculated by the difference in pain intensity between beginning and end responses. PPTs were tested at four sites [3 for local hypersensitivity (knee), 1 for widespread hypersensitivity (hand)]. CPM was conducted by comparing PPTs during two conditions (baseline, ice immersion). CPM response was defined as the percent difference between conditions. Between-group differences in TSP response were analyzed with a Welch's test. Separate Welch's tests analyzed group comparisons of PPTs and CPM responses at four sites. RESULTS: Females with PFP exhibited greater TSP response (P=0.019) and lower CPM response at patella center (P=0.010) and hand sites (P=0.007) than pain-free females. PPT group differences were not observed at any site (P>0.0125). CONCLUSIONS: Females with PFP modulate pain differently than pain-free females. Clinicians should recognize signs of central sensitization and their potential impact on treatment options.

Relations among visual strategies, force fluctuations, and attention during a force-matching task.

Greater understanding of how people use visual information to minimize force fluctuations provides critical insight into visuomotor processing. Visual strategies were examined during a force-matching task with different feedback displays. When only vertical feedback was provided, young healthy participants (N = 20, 9 men) fixated their gaze centrally. When vertical and horizontal visual feedback was provided, participants performed saccades to maintain gaze near the leading edge of the force trace. Performance on a separate attention task assessed visual and motor attention capabilities in the same participants. Selecting the correct saccade trajectory on the attention task was positively correlated with measures predicting performance on the force-matching task. Optimal visual strategies, combined with motor attention, may contribute to minimizing pinch force variability at low force.

The Kinetic Chain Has a Brain: Could Adding Cognitive Demands in Lower Limb Injury Prevention Programs Improve Outcomes?

SYNOPSIS: The most effective lower limb injury prevention programs include strength training, balance exercises, and instructions on how to land safely from a jump or hop. Yet, the programs are not 100% effective-lower extremity noncontact injuries continue to be a significant problem. We suggest that adding cognitive training to motor tasks that currently comprise current lower limb injury prevention programs might help clinicians, athletes, and coaches continue to make inroads into preventing knee injuries. We ground our hypotheses in robust findings from cognitive neuroscience and rehabilitation, suggesting that when task demands exceed the attentional capacity of an individual, the risk for noncontact lower extremity injuries increases. In this editorial, we explain the concepts of attentional capacity and attentional demands, and the interplay of the two in sport, to justify including cognitive tasks to injury prevention programs to improve outcomes. J Orthop Sports Phys Ther 2023;53(4):1-3. doi:10.2519/jospt.2023.11403.

The sacroiliac dysfunction and pain is associated with history of lower extremity sport related injuries.

BACKGROUND: The purpose of this study was to examine the association of sacroiliac joint (SIJ) dysfunction and pain with overuse and acute lower limb and pelvic girdle injuries of Iranian basketball players. METHODS: In this cross-sectional study, basketball-related injury data were collected during 2019-2020 from 204 basketball players of the Iranian league using the online Information Retrospective Injury Questionnaire. A researcher then performed ten clinical tests to assess SIJ dysfunction and pain (five tests for dysfunction and five tests for pain). Data analysis was performed by logistic regression at the confidence interval of 95%. RESULTS: Within our sample (n = 204), injury rates were calculated across sub-groups of athletes that had only SIJ pain (n = 19), only SIJ dysfunction (n = 67), both SIJ pain and dysfunction (n = 15) or no SIJ complaints (n = 103). Across these groups, a total of 464 injuries were reported. SIJ pain group reported 80 injuries (17.2%), SIJ dysfunction group reported 210 injuries (45.2%), both SIJ pain and dysfunction group reported 58 injuries (12.5%, and the no SIJ pain or SIJ dysfunction group reported 116 injuries (25.0%). Participants with SIJ pain were more likely to report previous pelvic girdle injuries (overuse: odds ratio (OR): 0.017; 95% CI: 0.005-0.56; p < 0.001 and acute: OR: 0.197; 95%CI: 0.101-0.384; p < 0.001) and also lower limb injuries (overuse: OR: 0.179, 95%CI: 0.082-0.392, p < 0.001). Participants with SIJ dysfunction only were likely to report acute pelvic girdle injuries (OR: 0.165; 95%CI: 0.070-0.387; p < 0.001) and acute lower limb injuries (OR: 0.165; 95%CI: 0.030-0.184; p < 0.001). CONCLUSION: The presence of SIJ dysfunction and pain is associated with a history of acute and overuse injuries in the pelvic girdle and lower limb. Thus, SIJ dysfunction and pain should be specifically evaluated and addressed when designing rehabilitation programs for sports-related injuries.

The effect of fatigue on electromechanical response times in basketball players with and without persistent low back pain.

Typically, athletes alter movement mechanics in the presence of back pain, but the effect of these changes on lower extremity injury risk is not well understood. This study aimed to compare the effect of fatigue on electromechanical response times during a choice reaction task in basketball players with and without persistent low back pain. Twenty-four male basketball players participated. Total reaction time (TRT), premotor time (PMT), and electromechanical delay (EMD data were recorded before and after fatigue. The chronic low back pain (CLBP) group had significantly longer EMD in Med gastrocnemius (p = 0.001) and Tibialis anterior (p = 0.001), and shorter EMD in Vastus Lateralis (p = 0.001), Vastus Medialis Oblique (p = 0.003), and Semitendinosus (p = 0.025) muscles after fatigue. PMT in the CLBP group had longer than the Non-CLBP in Vastus Lateralis (p = 0.010), Vastus Medialis Oblique (p = 0.017), Semitendinosus (p = 0.002). Also, TRT was longer in knee flexion (p = 0.001) and ankle plantarflexion (p = 0.001) muscle groups. The different effects of fatigue on electromechanical response times of the knee and ankle in people with CLBP may represent the effect of an axial injury on lower extremity injury risk factors in situations of higher cognitive load, similar to competitive play.

Lower Kinetic Chain, Meet the Thinking Brain: A Scoping Review of Cognitive Function and Lower Extremity Injury Risk.

The classic model of non-contact ACL injury includes environmental, anatomical, hormonal and biomechanical risk factors which directly impact either the amount of stress placed on the ligament or the relative capacity of ligament to withstand the forces placed on it. However, cognition also clearly plays a role in successful athletic performance, yet diminished cognitive function is rarely considered a risk factor for injury. Objective: To examine the existing literature to determine the extent to which cognitive function (both cognitive ability and task cognitive load) influences non-contact lower extremity injury risk in male and female athletes with a broad variety of athletic expertise. Study Design: Scoping Review. Methods: An electronic search was conducted of CINAHL, SPORTDiscus, Google Scholar, and MEDLINE using the PRISMA method. Search terms included Boolean combinations of "cognition", "concussion", "ImPACT", "cognitive deficit", "mild traumatic brain injury (mTBI)", and "neuropsychological function" as cognitive descriptors and the terms "injury risk" and "lower extremity injury" as injury descriptors. Inclusion criteria included papers written in English published between 2000-2021. Exclusion criteria included neurological and cognitively atypical populations, except for concussion (included). Included articles were appraised using the Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. Results: Fifty-six studies utilizing across the spectrum of levels of evidence met inclusion criteria. Forty-one articles had good, fourteen had fair, and one had poor methodological quality. Studies examined baseline cognitive function in healthy athletes (n=7); performance during dual-task paradigms (n=13); and the impact of concussion on dual-task performance (n=4), LE injury risk (n=22), or post-concussion testing (n=10). Six articles examining cognitive function and all dual-task studies (including concussion studies) found altered biomechanics associated with injury or increased processing demands. Studies related to concussion and injury incidence consistently found an increased risk of LE injury following concussion. Half of the studies that examined concussion and post-concussion cognitive testing demonstrated significant effects. Discussion: Consistent across participant demographics, tasks, and dependent measures, fifty-one of fifty-six assessed articles concluded that decreased cognitive ability or increased cognitive load led to risky LE mechanics or a direct increase in non-contact LE injury risk. Conclusion: The robustness of results across gender, performance level, sport, cognitive ability, task cognitive load suggest that the inclusion of cognitive training in the design of optimal LE injury prevention programs warrants further study. Level of Evidence: Ia.

Social cognition: LIP activity follows the leader.

A new study has found that, when a macaque monkey chooses where to look, activity in parietal cortex reflects anticipated reward value, whether from fluid to drink or from social information such as dominance.

Distinct saccade planning and endogenous visuospatial attention maps in parietal cortex: A basis for functional differences in sensory and motor attention.

Parietal cortex activity contributes to higher-level cognitive processes, including endogenous visual attention and saccade planning. While visual attention is the process of selecting pertinent information from the environment, saccade planning may involve motor attention in the planning of a specific movement, including the process of selecting the correct path. We isolated areas in parietal cortex involved in saccade planning, while controlling visual attention, to understand the relationship between the two processes. Using our novel stimulus, participants performed a delayed saccade task and an endogenous covert visuospatial attention task with peripheral targets in identical locations. We compared multiple target locations across the two domains at the level of the individual to better understand variability in the relationship between these two maps. The anterior-posterior organization of saccade planning and visual attention maps varied among, but not within, participants, and 14-29% of the maps for each task overlapped one another across hemispheres. Interestingly, within the region of co-activation, over 67% of the voxels responded to the same location for both tasks. These cortical areas of overlap may represent regions of the brain specifically involved in the transfer of information from vision to action along the visuomotor pathway. These results further establish the relationship between maps associated with saccade planning and visual attention at the individual level, indicating the lack of a single saliency map in parietal cortex.

Effects of Thresholding on Voxel-Wise Correspondence of Breath-Hold and Resting-State Maps of Cerebrovascular Reactivity.

Functional magnetic resonance imaging for presurgical brain mapping enables neurosurgeons to identify viable tissue near a site of operable pathology which might be at risk of surgery-induced damage. However, focal brain pathology (e.g., tumors) may selectively disrupt neurovascular coupling while leaving the underlying neurons functionally intact. Such neurovascular uncoupling can result in false negatives on brain activation maps thereby compromising their use for surgical planning. One way to detect potential neurovascular uncoupling is to map cerebrovascular reactivity using either an active breath-hold challenge or a passive resting-state scan. The equivalence of these two methods has yet to be fully established, especially at a voxel level of resolution. To quantitatively compare breath-hold and resting-state maps of cerebrovascular reactivity, we first identified threshold settings that optimized coverage of gray matter while minimizing false responses in white matter. When so optimized, the resting-state metric had moderately better gray matter coverage and specificity. We then assessed the spatial correspondence between the two metrics within cortical gray matter, again, across a wide range of thresholds. Optimal spatial correspondence was strongly dependent on threshold settings which if improperly set tended to produce statistically biased maps. When optimized, the two CVR maps did have moderately good correspondence with each other (mean accuracy of 73.6%). Our results show that while the breath-hold and resting-state maps may appear qualitatively similar they are not quantitatively identical at a voxel level of resolution.

Photobiomodulation preserves mitochondrial redox state and is retinoprotective in a rodent model of retinitis pigmentosa.

Photobiomodulation (PBM) by far-red (FR) to near-infrared (NIR) light has been demonstrated to restore the function of damaged mitochondria, increase the production of cytoprotective factors and prevent cell death. Our laboratory has shown that FR PBM improves functional and structural outcomes in animal models of retinal injury and retinal degenerative disease. The current study tested the hypothesis that a brief course of NIR (830 nm) PBM would preserve mitochondrial metabolic state and attenuate photoreceptor loss in a model of retinitis pigmentosa, the P23H transgenic rat. P23H rat pups were treated with 830 nm light (180 s; 25 mW/cm2; 4.5 J/cm2) using a light-emitting diode array (Quantum Devices, Barneveld, WI) from postnatal day (p) 10 to p25. Sham-treated rats were restrained, but not treated with 830 nm light. Retinal metabolic state, function and morphology were assessed at p30 by measurement of mitochondrial redox (NADH/FAD) state by 3D optical cryo-imaging, electroretinography (ERG), spectral-domain optical coherence tomography (SD-OCT), and histomorphometry. PBM preserved retinal metabolic state, retinal function, and retinal morphology in PBM-treated animals compared to the sham-treated group. PBM protected against the disruption of the oxidation state of the mitochondrial respiratory chain observed in sham-treated animals. Scotopic ERG responses over a range of flash intensities were significantly greater in PBM-treated rats compared to sham controls. SD-OCT studies and histological assessment showed that PBM preserved the structural integrity of the retina. These findings demonstrate for the first time a direct effect of NIR PBM on retinal mitochondrial redox status in a well-established model of retinal disease. They show that chronic proteotoxic stress disrupts retinal bioenergetics resulting in mitochondrial dysfunction, and retinal degeneration and that therapies normalizing mitochondrial metabolism have considerable potential for the treatment of retinal degenerative disease.

The representation of spatial attention in human parietal cortex dynamically modulates with performance.

The control and allocation of attention is an essential, ubiquitous neural process that gates our awareness of objects and events in the environment. Neural representations of the locus of spatial attention have been previously demonstrated in parietal cortex. However, the behavioral relevance of these neural representations is not known. While undergoing functional magnetic resonance imaging, subjects performed a covert spatial attention task that yielded a wide range of performance values. Voxels in parietal cortex selective for attended target location also dynamically modulated, becoming more or less responsive as performance levels changed. Surprisingly, this relationship was not linear. Responses peaked at intermediate performance levels and dropped both when performance was very high and when it was very low. Such dynamic modulation may represent a mechanism for organizing neural control signals according to behavioral task demands.

Work-related musculoskeletal disorders and injuries: differences among older and younger occupational and physical therapists.

INTRODUCTION: Occupational and physical therapists are at significant risk of work-related musculoskeletal disorders and injuries. As the therapy workforce ages, and shortages of therapists are predicted, it is important to evaluate differences in injuries and injury behaviors between older and younger therapists. METHODS: Half of all occupational and physical therapists practicing in Wisconsin were randomly selected for a cross sectional study examining the relationship between aging and characteristics of self-reported work injuries and musculoskeletal symptoms. RESULTS: Data from a sample of 1,158 therapists revealed older workers to have similar injury incidence rates, however, days away from work due to injury were higher among older workers. Overall, older and younger therapists were more similar than different, especially in regards to work behaviors. Older therapists tended to report more severe pain symptoms than younger therapists and were two and a half times more likely to report that they changed jobs due to their pain symptoms. CONCLUSIONS: Older and younger therapists have similar work-related injury experiences. Older workers may be more vulnerable to lost work time and may experience more severe pain symptoms. Many interventions exist to prevent work-related injuries to therapists and more guidance in the best way to integrate these interventions (e.g., mechanical lift devices) into therapy practice is needed.

Work-related musculoskeletal injuries and disorders among occupational and physical therapists.

Occupational therapists are at risk of work-related injuries (WRIs) because of the demanding nature of their work. However, information about WRIs and musculoskeletal disorders among occupational therapists is limited. For comparison, research indicates that up to 91% of physical therapists experience work-related musculoskeletal disorders (WMSDs) and pain. The purpose of this study was to gather new information about the prevalence, severity, and characteristics of work-related musculoskeletal symptoms and injuries among occupational therapists and to compare this information with physical therapists in the state of Wisconsin. Investigators mailed surveys to 3,297 randomly selected physical and occupational therapists living in Wisconsin. Results indicated a 2006 annual incidence rate of 16.5 injuries per 100 full-time workers among occupational therapists and 16.9 injuries per 100 full-time workers among physical therapists, a rate similar to workers employed in heavy manufacturing. Occupational therapists and physical therapists face similar and significant risks of injury and WMSDs.

Remote concussion history does not affect visually-guided reaching in young adult females.

AIM: We examined the long-term effects of concussions in young adult females on visuomotor behavior during a visually-guided reaching task of various complexities. MATERIALS & METHODS: 20 females with a history of longer than 6 months since a concussion and 20 healthy females quickly and accurately performed a delayed reach to a previously cued target. RESULTS: As both cognitive and motor load increased, task performance decreased for both groups (p < 0.05). However, contrary to our primary hypothesis, no differences in task performance were found between the two experimental groups (p > 0.05). CONCLUSION: The young adult females with a remote history of concussion demonstrated no deficits in visuomotor behavior on an attention-mediated reaching task as compared with control participants.

Divided attention during cutting influences lower extremity mechanics in female athletes.

Anterior cruciate ligament (ACL) injuries in basketball appear to be more common when players are in possession of the ball. The greater risk of ACL injury when in possession of the ball may result from the athlete's inability to fully attend to their movement. However, it is also possible that having to carry/manipulate the ball restricts the athlete's ability to utilise their upper extremities for stability during a manoeuvre. The purpose of this study was to explore how possession of a basketball and divided attention influence lower extremity mechanics during cutting and landing. Twenty uninjured females with basketball experience performed a baseline lateral cutting task, as well as lateral cuts while carrying a basketball, with and without a subsequent chest pass. Requiring participants to carry the basketball in isolation (i.e., without the additional pass) had minimal influence on lower extremity mechanics compared to baseline. However, participants demonstrated less knee flexion (40.9° vs. 47.3°) and greater knee abduction (12.2° vs. 10.1°) for trials that included the additional pass (divided attention condition) compared to trials conducted while carrying the basketball in isolation. Athletes may be at greater risk for ACL injury when they are unable to solely attend to their movement.

The need for mapping personal goals to exercise dosage in community-based exercise programs for people with Parkinson's disease.

Purpose: Community-based exercise can support long-term management of Parkinson's disease, although it is not known if personal goals are met in these programs. The objectives of this study were to: (1) examine the goals of community based exercise programs from the participant and instructor perspectives; (2) establish the extent to which these programs meet self-described exercise outcomes; and (3) explore participant and instructor perspectives on barriers to meeting exercise expectations. Materials and Methods: This study explores the experiences of people with Parkinson's disease participating in a structured exercise program at six community sites. A mixed-methods approach was used, including participant and instructor interviews, assessment of exercise intensity, and mapping of exercise dosage to participant goals. Twenty-four exercise participants provided interview, quality of life, and exercise intensity data. Results: Twenty-one participants exercised for primary management of their Parkinson's disease. None met the exercise dosage necessary to meet this primary objective, although 60% met exercise dosage required to prevent disuse deconditioning. Participants and instructors did not describe similar goals for the community-based exercise program. Conclusions: Community-based exercise programs could be optimized by better aligning participant goals and exercise intensity.