Purpose: To examine the effects of a high-carbohydrate diet (HCHO), periodized-carbohydrate (CHO) diet (PCHO), and ketogenic low-CHO high-fat diet (LCHF) on training capacity. Methods: Elite male racewalkers completed 3 weeks of periodic training while adhering to their dietary intervention. Twenty-nine data sets were collected from 21 athletes. Each week, 6 mandatory training sessions were completed, with additional sessions performed at the athlete’s discretion. Mandatory sessions included an interval session (10 × 1-km efforts on a 6-min cycle), tempo session (14 km with a 450-m elevation gain), 2 long walks (25–40 km), and 2 easy walks (8–12 km) where “sleep-low” and “train-low” dietary strategies were employed for PCHO. Racewalking speed, heart rate, rating of perceived exhaustion, and blood metabolites were collected around key sessions. Results: LCHF covered less total distance than HCHO and PCHO (P < .001); however, no differences in training load between groups were evident (P = .285). During the interval sessions, walking speed was slower in LCHF (P = .001), equating to a 2.8% and 5.6% faster speed in HCHO and PCHO, respectively. LCHF was also 3.2% slower in completing the tempo session than HCHO and PCHO (P = .001). Heart rate was higher (P = .002) and lactate concentrations were lower (P < .001) in LCHF compared to other groups, despite slower walking speeds during the interval session. No between-groups differences in rating of perceived exhaustion were evident (P = .077). Conclusion: Athletes adhering to an LCHF diet showed impaired training capacity relative to their high-CHO-supported counterparts, completing lower training volumes at slower speeds, with higher heart rates.
Alannah K.A. McKay, Megan L.R. Ross, Nicolin Tee, Avish P. Sharma, Jill J. Leckey, and Louise M. Burke
Sally Paulson, Joshua L. Gills, Anthony Campitelli, Megan D. Jones, Joohee I. Sanders, Jordan M. Glenn, Erica N. Madero, Jennifer L. Vincenzo, Christopher S. Walter, and Michelle Gray
Prior work, primarily focusing on habitual gait velocity, has demonstrated a cost while walking when coupled with a cognitive task. The cost of dual-task walking is exacerbated with age and complexity of the cognitive or motor task. However, few studies have examined the dual-task cost associated with maximal gait velocity. Thus, this cross-sectional study examined age-related changes in dual-task (serial subtraction) walking at two velocities. Participants were classified by age: young-old (45–64 years), middle-old (65–79 years), and oldest-old (≥80 years). They completed single- and dual-task walking trials for each velocity: habitual (N = 217) and maximal (N = 194). While no significant Group × Condition interactions existed for habitual or maximal gait velocities, the main effects for both condition and age groups were significant (p < .01). Maximal dual-task cost (p = .01) was significantly greater in the oldest-old group. With age, both dual-task velocities decreased. Maximal dual-task cost was greatest for the oldest-old group.
Mohsen Shafizadeh, Stuart Bonner, Jonathan Fraser, Shahab Parvinpour, Mohsen Shabani, and Andrew Barnes
The aim of this study was to compare the interlimb coordination, asymmetry, and variability between older adults who participated in sports (n = 25; age = 72.6 ± 6.46 years) and sedentary older adults (n = 20; age = 70.85 ± 3.82 years). The sport participants were selected from tennis and badminton clubs, whereas the sedentary participants were recruited from local community centers. The participants walked at their preferred speed in a 10-m walkway for 2 min. The interlimb coordination was measured by the phase coordination index. Other walking metrics were speed, cadence, swing time, stance time, double-support time, stride time, and swing time asymmetry. The results showed that the sport participants relative to the sedentary group had better interlimb coordination, higher walking speed and cadence, and less swing time variability. Young older adults also had a better interlimb coordination. In conclusion, the findings of this study showed that long-term participation in sports has some antiaging benefits on gait coordination and symmetry in older adults.
Amy Cox and Ryan E. Rhodes
The onset of retirement and children leaving the family home may offer a “window of opportunity” for individuals to influence regular moderate- to vigorous-intensity physical activity; therefore, this study examines the feasibility of a moderate- to vigorous-intensity physical activity intervention among recently retired participants (RET) and parents (P) with children who recently left the family home. A total of 46 inactive RET and nine inactive P were randomized to a 10-week web intervention (n = RET = 25/P = 4) or waitlist control (n = RET = 21/P = 5). Intervention techniques followed the multiprocess action control framework. Enrollment (37.5% for P; 40% for RET), retention (89% for P; 83% for RET), and satisfaction were high. One hundred percent of intervention-sectioned participation increased moderate- to vigorous-intensity physical activity compared with 52% of controls; large effect size differences were observed for key multiprocess action control constructs. Participants were highly satisfied with the intervention; however, recruitment challenges of P support moving to a randomized controlled trial for only the RET group.
Marcos Rescarolli, Francisco Timbó de Paiva Neto, Adalberto Aparecido dos Santos Lopes, Marcelo Dutra Della Justina, Anna Quialheiro Abreu da Silva, Eleonora d’Orsi, and Cassiano Ricardo Rech
This study aimed to examine the relationship between Walk Score index with walking to commuting, moderate-to-vigorous physical activity, and screen time in older adults. Georeferenced addresses were entered into the Walk Score platform. Walking to commute and moderate-to-vigorous physical activity were assessed using the International Physical Activity Questionnaire and categorized according to the World Health Organization recommendations. Screen time was analyzed through self-reported time watching television/being on the computer. We used binary logistic regression to estimate the association between variables. Older adults who lived in places with higher Walk Score had a higher prevalence of walking to commuting (odds ratio = 1.73; 95% confidence interval [1.18, 2.55]) and engaging in moderate-to-vigorous physical activity (odds ratio = 1.76; 95% confidence interval [1.05, 2.98]). A relationship also was observed between higher Walk Score and more time in screen time (odds ratio = 1.67; 95% confidence interval [1.19, 2.34]). The results showed that residing in a more walkable neighborhood increased the chances of the older adults spending 3 hr or more in front of a screen.
