The Relationship between Physical Activity, Sleep Quality, and Stress: A Study of Teachers during the COVID-19 Pandemic.

The COVID-19 pandemic prompted chaotic changes in the daily lives of K-12 teachers, resulting in increased stress and other mental health problems. Limited evidence regarding the relationship between physical activity, sleep, and perceived stress among teachers during the COVID-19 pandemic exists. Therefore, the purpose of this study was to investigate the association between physical activity, sleep quality, and perceived psychological stress among teachers during the COVID-19 pandemic. An online survey measuring physical activity, sleep quality, and perceived psychological stress was distributed across 47 US states between September and October of 2020. Data provided by 635 teachers (mean age: 42 ± 18 years, 74.6% female) were included in the present analysis. Results suggested a negative association between physical activity and perceived psychological stress. Mediation analyses indicated that teachers engaging in high levels of physical activity were more likely to have good quality sleep and, in turn, were less likely to report high levels of perceived stress. Physical activity and sleep-related interventions could help curtail the rising levels of psychological distress amongst K-12 teachers during stressful times such as the COVID-19 pandemic. Teachers, especially those that self-report as female and/or young, report high levels of stress. These high levels of stress are a serious challenge for school districts in terms of attracting and retaining qualified teachers in K-12 classrooms.

Time spent in different sedentary activity domains across adolescence: a follow-up study

Abstract Objective: This longitudinal study aimed to verify possible changes in the time spent in sedentary activities occurring as screen-time, educational, cultural, social, and transportation domains in a sample of Brazilian adolescents between 2015 and 2017. Methods: It is a longitudinal prospective study with 586 adolescents from 12 to 15 years old at the Baseline (2015) enrolled in 14 public schools from Curitiba, Brazil. The Adolescent Sedentary Activity Questionnaire assessed the time spent in sedentary activities in five domains (recreational screen-time, educational, cultural, social, and transportation). A series of linear random effects regressions analyzed changes in the sedentary time between 2015 and 2017, with p < .05. Results: Overall, 323 adolescents dropped out of the study resulting in a retention rate of 44.9%. The overall sedentary time remained stable from 2015 to 2017 (-3.98 min/day, 95%CI: -15.39; 7.42). The screen-time decreased (-22.22 min/day, 95%CI: -30.30; -14.15), and educational (8.29 min/day, 95% CI: 3.52; 13.06), cultural (3.41 min/day, 95% CI: 0.66; 6.15) and social sedentary activities (8.20 min/day, 95% CI: 2.06; 14.34) increased from 2015 to 2017. Conclusion: Significant reductions in screen-time were evidenced along with increases in time spent on other sedentary activities of educational, cultural, and social nature.

Time spent in different sedentary activity domains across adolescence: a follow-up study.

OBJECTIVE: This longitudinal study aimed to verify possible changes in the time spent in sedentary activities occurring as screen-time, educational, cultural, social, and transportation domains in a sample of Brazilian adolescents between 2015 and 2017. METHODS: It is a longitudinal prospective study with 586 adolescents from 12 to 15 years old at the Baseline (2015) enrolled in 14 public schools from Curitiba, Brazil. The Adolescent Sedentary Activity Questionnaire assessed the time spent in sedentary activities in five domains (recreational screen-time, educational, cultural, social, and transportation). A series of linear random effects regressions analyzed changes in the sedentary time between 2015 and 2017, with p < .05. RESULTS: Overall, 323 adolescents dropped out of the study resulting in a retention rate of 44.9%. The overall sedentary time remained stable from 2015 to 2017 (-3.98 min/day, 95%CI: -15.39; 7.42). The screen-time decreased (-22.22 min/day, 95%CI: -30.30; -14.15), and educational (8.29 min/day, 95% CI: 3.52; 13.06), cultural (3.41 min/day, 95% CI: 0.66; 6.15) and social sedentary activities (8.20 min/day, 95% CI: 2.06; 14.34) increased from 2015 to 2017. CONCLUSION: Significant reductions in screen-time were evidenced along with increases in time spent on other sedentary activities of educational, cultural, and social nature. KeywordsSedentary behavior, Adolescent health, Longitudinal studies.

Time trends of physical inactivity in Brazilian adults from 2009 to 2017.

OBJECTIVE: The aim was to evaluate the changes in the prevalence of physical inactivity in the Brazilian adults from 2009-2017. METHODS: This study used a time-series research design based on the cross-sectional data of 462,498 Brazilian adults from 2009-2017. Participants were classified as physically inactive if they indicated not participating in physical activity in the last three months. The Prais-Winsten regression analyzed physical inactivity trends over time. RESULTS: The overall prevalence of physical inactivity was stable (p>0.05). Physical inactivity increased for women in four state capitals (annual growth rate: Goiânia 1.62%, Campo Grande 3.28%, Porto Velho 0.93%, and Vitória 2.09%) and decreased in one (annual growth rate: Rio Branco 4.50%). Physical inactivity decreased for men in four state capitals (annual growth rate: Campo Grande 4.72%, Natal 2.73%, São Luís 4.94%, and Rio Branco 2.95%). CONCLUSION: The physical inactivity among the Brazilian adults was stable between 2009 and 2017. Physical inactivity increased in women from Goiânia, Campo Grande, Porto Velho, and Vitória and decreased in women from Rio Branco and in men from Campo Grande, Natal, São Luís, and Rio Branco.

The Relationship between Psychological Stress and Healthy Lifestyle Behaviors during COVID-19 among Students in a US Midwest University.

The gripping coronavirus disease (COVID-19) has imposed dramatic changes to many areas of daily living in all sectors of society across the world. We examined the relationship between perceived stress and health behaviors among college students during the COVID-19 pandemic. An online survey with measures of psychological stress, physical activity and exercise, and sleep and social connectedness was distributed in June and July of 2020. The survey was completed by 550 college students (mean age: 21.3 ± 3.8 years, 74.2% female, 94.4% Caucasian). Being female and unemployed and having a lower annual income were significantly associated with higher levels of stress. In addition, regression analysis found that reduced exercise and sleep during the COVID-19 pandemic significantly predicted the levels of stress of participants after controlling for gender, employment status, and annual income. University officials should aim to implement health-promotion strategies directed at preventing reductions in exercise and sleep duration, especially in those at greater risk of increased perceived stress such as females and economically disadvantaged students.

Associations between physical activity, sedentary behavior, and health risk behaviors among adolescents from a city in Southern Brazil / Associações entre atividade física, comportamento sedentário e comportamentos de risco à saúde entre adolescentes de uma cidade do Sul do Brasil

This study examined the independent and combined associations of physical activity (PA) and sedentary behavior (SB) with health risk behaviors in Brazilian adolescents. Participants were 893 adolescents (454 girls) from Curitiba, Brazil. The Youth Activity Profile questionnaire evaluated PA and the Adolescent Sedentary Questionnaire evaluated SB. The Youth Risk Behavior Surveillance System ( YRBS) questionnaire evaluated fruit, vegetable, alcohol, and tobacco consumption. Binary Logistic regression measured the independent and combined associations of PA and SB with risk behaviors. PA was inversely associated with low fruit (OR = 0.30; 95%CI: 0.18-0.51) and vegetable consumption (OR = 0.43; 95%CI: 0.25-0.73), and tobacco use (OR = 0.52; 95%CI: 0.29-0.89). However, PA was positively associated with mild (OR = 1.54; 95%CI: 1.08-2.19) and excessive alcohol use (OR = 1.53; 95%CI: 1.01-2.33). Higher levels of PA were associated with reduced risks of smoking and healthier eating patterns, but higher likelihood of alcohol consumption

Este estudo examinou as associações independentes e combinadas de atividade física (AF) e do comportamento sedentário (CS) com comportamentos de risco à saúde em adolescentes brasileiros. Participaram do estudo 893 adolescentes (454 meninas) de Curitiba, Brasil. O questionário Youth Activity Profile avaliou a AF e o Questionário de atividades sedentárias dos adolescentes avaliou o CS. O questionário Youth Risk Behavior Surveillance System (YRBS) avaliou o consumo de frutas, vegetais, álcool e tabaco. A regressão logística binária avaliou as associações independentes e combinadas de AF e CS com comportamentos de risco. AF foi inversamente associado com baixo consumo de frutas (OR = 0,30; IC95%: 0,18-0,51), de vegetais (OR = 0,43; IC95%: 0,25-0,73) e uso de tabaco (OR = 0,52; IC95%: 0,29-0,89). No entanto, a AF foi positivamente associada com uso moderado (OR = 1,54; IC95%: 1,08-2,19) e uso excessivo de álcool (OR = 1,53; IC95%: 1,01-2,33). Níveis mais altos de AF foram associados com riscos reduzidos de fumar e padrões alimentares mais saudáveis e com maior probabilidade de consumo de álcool

Development and validation of the Brazilian Weight Teasing during Physical Activity Scale / Desenvolvimento e validação da Escala Brasileira de Provocações Referente ao Peso durante Atividade Física

Weight-related teasing is associated with loneliness, depression, eating disorders, and less physical activity. The purpose of the study was to develop the Brazilian Weight Teasing during Physical Activity scale (WTPAS-BR) and gather validity evidence to support its use in Brazilian adolescents. In phase 1, the prototype scale was adjusted. In phase 2, the prototype scale was cross-culturally adapted into the WTPAS-BR. In phase 3, the WTPAS-BR was psychometrically assessed. Adjustments to the prototype scale qualified items to measure weight-related teasing. A rigorous and systematic cross-cultural adaptation process translated, and assessed the content and adequacy of the WTPAS-BR among Brazilian adolescents. Based on the factorial assessment of WTPAS-BR, a one-factor model with four items was adopted. The WTPAS-BR showed adequate internal consistency, convergent validity, and test-retest reliability. Strong validity evidence supports the use of the WTPAS-BR to measure weight-related teasing occurring during physical activity in Brazilian adolescents...(AU)

A provocação relacionada ao peso corporal está associada com solidão, depressão, distúrbios alimentares e baixa atividade física. O objetivo deste estudo foi desenvolver a Escala Brasileira de Provocação relacionada ao Peso Corporal durante a Atividade Física (PPCAF-BR) e reunir evidências de validade para apoiar seu uso em adolescentes brasileiros. Na fase 1, ajustes foram feitos em uma escala protótipo. Na fase 2, esta escala foi adaptada culturalmente para a PPCAF-BR. Na fase 3, a PPCAF-BR foi avaliada psicometricamente. As adaptações realizadas na escala protótipo qualificaram os itens para a avaliação de provocações referentes ao peso corporal. A tradução e a adequação da PPCAF-BR em adolescentes brasileiros foi obtida através de uma rigorosa e sistemática adaptação transcultural. Baseado na análise fatorial, foi adotado um modelo de um fator com quatro itens. A PPCAF-BR apresentou consistência interna, validade convergente e reprodutibilidade teste-reteste adequadas. Fortes evidências de validade suportam a utilização da PPCAF-BR para medir a provocação relacionada ao peso corporal ocorrida durante a atividade física em adolescentes brasileiros...(AU)

Discrimination against Obese Exercise Clients: An Experimental Study of Personal Trainers.

The aim of the study was to compare exercise recommendations, attitudes, and behaviors of personal trainers toward clients of different weight statuses. Fifty-two personal trainers participated in the study. The data collection was organized into two phases. In phase one, trainers read a profile and watched the video displaying an interview of either an obese or an average-weight client. Profiles and video interviews were identical except for weight status. Then, trainers provided exercise recommendations and rated their attitude toward the client. In phase two, trainers personally met an obese or an average-weight mock client. Measures were duration and number of advices provided by the trainer to a question posed by the client and sitting distance between trainer and client. There were no significant differences in exercise intensity (p = .94), duration of first session (p = .65), and total exercise duration of first week (p = .76) prescribed to the obese and average-weight clients. The attitude of the personal trainers toward the obese client were not significantly different from the attitude of personal trainers toward the average-weight client (p = .58). The number of advices provided (p = .49), the duration of the answer (p = .55), and the distance personal trainers sat from the obese client (p = .68) were not significantly different from the behaviors displayed toward the average-weight client. Personal trainers did not discriminate against obese clients in professional settings.

The relationship of movement skills with habitual and organized physical activity in seven and eight-year-old children / Associação entre habilidades motoras e atividade física habitual e organizada em crianças de sete e oito anos / Asociación entre habilidades motrices y actividad física habitual y organizada en niños de siete y ocho años

PURPOSE: To verify the association of motor skills with habitual and organized PA partici-pation, and sedentary behavior for males and females. METHODS: The study employed a cross-sectional design in a sample of seventy-six second graders from a public elementary school in a Midwestern State. RESULTS: Mann Whitney and t-tests indicated gender differ-ences in FMS and PA variables. Spearman correlation analyses demonstrated that habitual PA was correlated to total FMS, and manipulative skills for boys. For girls, a significant associa-tion was present in organized PA and locomotor skills. CONCLUSION: Choice of organized physical activity seems to influence the development of FMS and affect habitual PA behavior differently in boys and girls.

OBJETIVO: Verificar as associações de Habilidades Motoras Fundamentais (HMF) com a participação em Atividade Física (AF) e comportamento sedentário em meninos e meninas. MÉTODO: O estudo utilizou um delineamento transversal em uma amostra de alunos de es-cola pública. RESULTADOS: Mann Whitney e testes-t indicaram diferenças de gênero na HMF e variáveis de AF e comportamento sedentário. As análises de correlação demonstraram que AF habitual esteve significativamente associada com HMF total e manipulação de objetos nos meninos. Para as meninas, associações significativas foram observadas entre AF organi-zada e habilidades locomotoras. CONCLUSÃO: A participação em AF organizada parece influenciar o desenvolvimento de habilidades motoras e o comportamento de AF habitual.

OBJETIVO: Verificar asociaciones entre las HABILIDADES MOTORAS FUNDAMEN-TALES (HMF) con la participación en Actividad Física (AF) y el comportamiento sedentario. MÉTODO: El estudio utilizó un diseño transversal en una muestra de estudiantes de escuela pública. RESULTADOS: Mann-Whitney y testes-t indicaron diferencias de género en varia-bles de HMF, AF y el comportamiento sedentario. Los análisis de correlación demostraron que la AF habitual estuvo significativamente asociada con HMF total y manipulación de obje-tos en los niños. Para las niñas, asociaciones significativas fueron observadas entre AF orga-nizada y habilidades locomotoras. CONCLUSIÓN: La participación en AF organizada parece influir en el desarrollo de las habilidades motoras y el comportamiento de la AF habitual.

Relative Age Effect and Academic Timing in American Junior College Baseball.

Previous research has shown that older athletes within age groupings are often perceived to be more talented simply due to advanced maturity, leading to biased selection in higher levels of sports competition, now commonly termed relative age effect (RAE). This study's goals were to determine whether (a) RAE influenced the selection of junior college baseball participants and (b) academic timing ( Glamser & Marciani, 1992 ), in which academic status determines age groupings more than strict age guidelines for college sports, influenced the formation of RAE. Participants were 150 junior college baseball players. Our results showed that RAE was only a significant factor, comparing the birth distribution of participants born before and after the midpoint of the participation year, when academic timing was also a factor in determining age groupings. In addition, the birth rate distribution, though not significantly different than expected, was greater only when those participants born during the expected participation year were included. The results of this study indicate that RAE could bear more influence among American student-athletes than was previously reported in that RAE in conjunction with academic timing does influence the selection of collegiate athletes.

ASSOCIATION BETWEEN WEIGHT-TEASING AND PHYSICAL ACTIVITY IN ADOLESCENTS. / ASSOCIAÇÃO ENTRE A PROVOCAÇÃO REFERENTE AO PESO CORPORAL E A ATIVIDADE FÍSICA EM ADOLESCENTES.

OBJECTIVE: The aim of the study was to determine the association between weight-teasing and physical activity in students from public schools of Curitiba, Paraná (Southern Brazil). METHODS: The sample consisted of 95 students (48 boys and 47 girls) aged 12 to 14 years old. The Perception of Weight Teasing (POTS) and The Perception of Weight Teasing during Physical Activity Scale assessed the frequency of weight-teasing experienced by the participants. Accelerometers measured physical activity. BMI assessed the weight status of the participants. Pearson correlations analyzed the association between the teasing and physical activity variables at a significance level of 0.05. RESULTS: The relationship between teasing variables and physical activity was not significant. A large proportion of participants failed to meet the recommended levels of physical activity regardless of sex (72%), and girls were significantly less physically active than boys (56.3% of boys and 89.4% of girls; p<0.01). CONCLUSIONS: Some participants were targets of weight-teasing, but teasing was not related to physical activity. Interventions are necessary to educate middle school students about the harmful consequences of weight teasing.

OBJETIVO: Investigar a associação entre a atividade física e a provocação referente ao peso corporal em escolares matriculados no sistema público de ensino em Curitiba, Paraná. MÉTODOS: A amostra foi composta por 95 escolares (48 meninos e 47 meninas) com idades entre 12 e 14 anos. Para avaliar a provocação, foram utilizadas as versões em português da Escala de Percepção de Provocação e a Escala de Percepção de Provocação Durante a Atividade Física. A atividade física foi mensurada por meio de acelerômetros. O Índice de Massa Corporal (IMC) foi utilizado para definição do estado nutricional dos participantes. A associação entre as variáveis de provocação e de atividade física foi analisada por meio da correlação de Pearson, adotando um nível de significância de 0,05. RESULTADOS: Não foram verificadas associações significativas entre as variáveis de provocação e atividade física. Foram observados valores elevados de indivíduos insuficientemente ativos (72%), com diferenças significativas entre os sexos (56,3% dos meninos e 89,4% das meninas, p<0,01). CONCLUSÕES: A provocação referente ao peso é vivenciada pelos escolares avaliados e não esteve relacionada com a atividade física. Destaca-se a importância de intervenções que incentivem a conscientização das consequências da provocação referente ao peso.

Associação entre a provocação referente ao peso corporal e a atividade física em adolescentes / Association between weight-teasing and physical activity in adolescents

RESUMO Objetivo: Investigar a associação entre a atividade física e a provocação referente ao peso corporal em escolares matriculados no sistema público de ensino em Curitiba, Paraná. Métodos: A amostra foi composta por 95 escolares (48 meninos e 47 meninas) com idades entre 12 e 14 anos. Para avaliar a provocação, foram utilizadas as versões em português da Escala de Percepção de Provocação e a Escala de Percepção de Provocação Durante a Atividade Física. A atividade física foi mensurada por meio de acelerômetros. O Índice de Massa Corporal (IMC) foi utilizado para definição do estado nutricional dos participantes. A associação entre as variáveis de provocação e de atividade física foi analisada por meio da correlação de Pearson, adotando um nível de significância de 0,05. Resultados: Não foram verificadas associações significativas entre as variáveis de provocação e atividade física. Foram observados valores elevados de indivíduos insuficientemente ativos (72%), com diferenças significativas entre os sexos (56,3% dos meninos e 89,4% das meninas, p<0,01). Conclusões: A provocação referente ao peso é vivenciada pelos escolares avaliados e não esteve relacionada com a atividade física. Destaca-se a importância de intervenções que incentivem a conscientização das consequências da provocação referente ao peso.

ABSTRACT Objective: The aim of the study was to determine the association between weight-teasing and physical activity in students from public schools of Curitiba, Paraná (Southern Brazil). Methods: The sample consisted of 95 students (48 boys and 47 girls) aged 12 to 14 years old. The Perception of Weight Teasing (POTS) and The Perception of Weight Teasing during Physical Activity Scale assessed the frequency of weight-teasing experienced by the participants. Accelerometers measured physical activity. BMI assessed the weight status of the participants. Pearson correlations analyzed the association between the teasing and physical activity variables at a significance level of 0.05. Results: The relationship between teasing variables and physical activity was not significant. A large proportion of participants failed to meet the recommended levels of physical activity regardless of sex (72%), and girls were significantly less physically active than boys (56.3% of boys and 89.4% of girls; p<0.01). Conclusions: Some participants were targets of weight-teasing, but teasing was not related to physical activity. Interventions are necessary to educate middle school students about the harmful consequences of weight teasing.

Step-count guidelines referenced on 60-minutes of moderate/vigorous physical activity

The purpose of this study was to establish step-count guidelines for sixth-grade students and assess the ability of step-counts to discriminate between students achieving and not achieving 60-minutes of moderate to vigorous physical activity daily. 201 sixth-grade students completed the study. They wore a pedometer and an accelerometer at the waist level for one full day. ROC curves were used to establish step-count guidelines and determine the diagnostic accuracy of step-counts. Sixth grade students need 12,118 steps/day to reach adequate daily levels of physical activity. The AUC indicated good diagnostic accuracy of step-counts. Suggested step-count guidelines can be a useful tool for identifying children who need to increase their daily levels of physical activity. The step-count cutoff proposed in this study is adequate for discriminating between sixth grade students reaching and not reaching recommended levels of physical activity.

O objetivo deste estudo foi estabelecer diretrizes de passos por dia para estudantes da sexta série escolar e avaliar a possibilidade da contagem de passos para discriminar estudantes que atendem ou não a recomendação de 60 minutos diários de atividade física de moderada a vigorosa intensidade. 201 estudantes completaram o estudo. Ele usaram pedômetros e acelerômetros na cintura por 1 dia inteiro. Curvas ROC foram utilizadas para estabelecer diretrizes e precisão diagnóstica da contagem de passos. A AUC indicou boa capacidade diagnóstica da contagem de passos. Para atender níveis adequados de atividade física, 12.118 passos/dia são recomendados para estudantes da sexta série. Recomendações de contagem de passos sugeridas podem ser uma ferramenta útil para identificar crianças que necessitam aumentar seu nível diário de atividade física. O ponto de corte de passos/dia proposto neste estudo é adequado para discriminar estudantes de sexta série que atendem ou não níveis recomendados de atividade física.

El propósito de este estudio fue a establecerse directrices de pasos/día para los estudiantes de sexto grado y evaluar la capacidad de pasos/día para discriminar entre los estudiantes que alcanzan y no alcanzan 60 minutos de actividad física moderada a vigorosa. 201 estudiantes de sexto grado finalizaron el estudio. Ellos usaran un podómetro y un acelerómetro en el nivel de la cintura por un día completo. Se utilizaron curvas ROC para establecerse directrices y la exactitud diagnóstica de pasos/día. Para alcanzar un nivel adecuado de actividad física, se recomienda 12.118 pasos/día. El AUC mostró buena capacidad diagnóstica de pasos/día. Directrices de pasos/día sugeridos pueden ser una herramienta útil para la identificación de los niños que necesitan incrementar sus niveles de actividad física. El punto de corte de pasos/día propuesto es adecuado para discriminar entre los estudiantes que alcanzan y no alcanzan a los niveles recomendados de actividad física diario.

Step-Count Guidelines for Children and Adolescents: A Systematic Review.

BACKGROUND: The aim of this systematic review was to identify the most optimal step-count cutoff for children and adolescents (5-19 years old) among guidelines currently available in the literature. METHODS: The databases searched were PubMed, SportDiscus, Science Direct, Web of Science and LILACS. Studies were categorized into Health Cohort studies or Physical Activity (PA) Cohort studies according to the reference standard used. The quality of the studies was assessed using the QUADAS-2 instrument. RESULTS: Six Health and 3 PA Cohort studies were included in the final pool of papers after Full Text reading. With the exception of a single study, studies demonstrated a high risk of methodological bias in at least 1 of the QUADAS-2 domains. Guidelines ranged from 10,000 to 16,000 steps/day for the Health studies (5-16 years old), and from 9,000 to 14,000 steps/day for PA studies (6-19 years old). Due to the high risk of methodological bias, none of the Health Cohort guidelines were endorsed. The PA Cohort study with the lowest risk of methodological bias suggested 12,000 steps/day for children and adolescents irrespective of gender. CONCLUSION: PA Cohort studies demonstrated lower risk of methodological bias than Health Cohort studies. The optimal youth step-count guideline of 12,000 steps/day was endorsed.

An electromyographic comparison of a modified version of the plank with a long lever and posterior tilt versus the traditional plank exercise.

The purpose of the study was to compare core muscle activation of the tradition prone plank with a modified version performed with a long-lever and posterior-tilt using surface electromyography. To further determine if a specific component of this modified plank was more effective than the other in enhancing muscle activity, the plank with a long lever and the plank with a posterior pelvic tilt were studied individually. Nineteen participants performed all four variations of the plank for 30 seconds in a randomized order with 5-minute rest between exercise bouts. Compared to the traditional prone plank, the long-lever posterior-tilt plank displayed a significantly increased activation of the upper rectus abdominis (p < 0.001), lower abdominal stabilizers (p < 0.001), and external oblique (p < 0.001). The long-lever plank showed significantly greater activity compared to the traditional plank in the upper rectus abdominis (p = 0.015) and lower abdominal stabilizers (p < 0.001), while the posterior tilt plank elicited greater activity in the external oblique (p = 0.028). In conclusion, the long-lever posterior-tilt plank significantly increases muscle activation compared to the traditional prone plank. The long-lever component tends to contribute more to these differences than the posterior-tilt component.

Muscle activation during low- versus high-load resistance training in well-trained men.

PURPOSE: It has been hypothesized that lifting light loads to muscular failure will activate the full spectrum of MUs and thus bring about muscular adaptations similar to high-load training. The purpose of this study was to investigate EMG activity during low- versus high-load training during performance of a multi-joint exercise by well-trained subjects. METHODS: Employing a within-subject design, 10 young, resistance-trained men performed sets of the leg press at different intensities of load: a high-load (HL) set at 75% of 1-RM and a low-load (LL) set at 30% of 1-RM. The order of performance of the exercises was counterbalanced between participants, so that half of the subjects performed LL first and the other half performed HL first, separated by 15 min rest. Surface electromyography (EMG) was used to assess mean and peak muscle activation of the vastus medialis, vastus lateralis, rectus femoris, and biceps femoris. RESULTS: Significant main effects for trials and muscles were found (p < 0.01). Significantly greater peak EMG activity was found during the HL set (M = 177.3, SD = 89.53) compared to the LL set (M = 137.73, SD = 95.35). Significantly greater mean EMG activity was found during the HL set (M = 63.7, SD = 37.23) compared to the LL set (M = 41.63, SD = 28.03). CONCLUSIONS: Results indicate that training with a load of 30% 1-RM to momentary muscular failure does not maximally activate the full motor unit pool of the quadriceps femoris and hamstrings during performance of multi-joint lower body exercise.

The effect of load reductions on repetition performance for commonly performed multijoint resistance exercises.

The purpose of this study was to compare 4 different loading schemes for the free weight bench press, wide grip front lat pull-down, and free weight back squat to determine the extent of progressive load reductions necessary to maintain repetition performance. Thirty-two recreationally trained women (age = 29.34 ± 4.58 years, body mass = 59.61 ± 4.72 kg, height = 162.06 ± 4.04 cm) performed 4 resistance exercise sessions that involved 3 sets of the free weight bench press, wide grip front lat pull-down, and free weight back squat, performed in this exercise order during all 4 sessions. Each of the 4 sessions was conducted under different randomly ordered loading schemes, including (a) a constant 10 repetition maximum (RM) load for all 3 sets and for all 3 exercises, (b) a 5% reduction after the first and second sets for all the 3 exercises, (c) a 10% reduction after the first and second sets for all the 3 exercises, and (d) a 15% reduction after the first and second sets for all the 3 exercises. The results indicated that for the wide grip front lat pull-down and free weight back squat, a 10% load reduction was necessary after the first and second sets to accomplish 10 repetitions on all the 3 sets. For the free weight bench press, a load reduction between 10 and 15% was necessary; specifically, a 10% reduction was insufficient and a 15% reduction was excessive, as evidenced by significantly >10 repetitions on the second and third sets for this exercise (p ≤ 0.05). In conclusion, the results of this study indicate that a resistance training prescription that involves 1-minute rest intervals between multiple 10RM sets does require load reductions to maintain repetition performance. Practitioners might apply these results by considering an approximate 10% load reduction after the first and second sets for the exercises examined, when training women of similar characteristics as in this study.

A comparison of trunk muscle activation: Ab Circle vs. traditional modalities.

The purpose of this study was to compare the activation of the rectus abdominis (RA), external oblique abdominis (EO), lower abdominal stabilizers (LASs), and lumbar erector spinae (LES) during performance of 3 traditional trunk exercises vs. exercise on the Ab Circle device. Surface electromyography was used to assess 12 subjects (6 men, 6 women) for 6 exercise conditions, including: abdominal crunch, side bridge, quadruped, and Ab Circle levels 1-3. For the RA, the abdominal crunch elicited significantly greater activity vs. the Ab Circle level 1, and the side bridge elicited significantly greater activity vs. the Ab Circle levels 1 and 2. For the EO, the side bridge elicited significantly greater activity vs. the quadruped. No significant differences were noted between conditions for the LASs. For the LES, the side bridge and quadruped elicited significantly greater activity vs. the abdominal crunch. The results of this study indicate that the anterior, posterior, and lateral trunk musculature can be activated to similar or even greater levels by performing the 3 traditional trunk exercises vs. the Ab Circle. This was particularly evident for the side bridge exercise, which elicited significantly greater activity of the RA vs. the Ab Circle levels 1 and 2, and elicited similar activity of the EO, LASs, and LES at all 3 Ab Circle levels.

Strength increases in upper and lower body are larger with longer inter-set rest intervals in trained men.

The purpose of the current study was to compare different rest interval durations on upper and lower body strength. Thirty-six recreationally trained men were randomly assigned to 1 min (G1; n=12), 3 min (G3; n=12) or 5 min (G5; n=12) rest interval groups. Each group performed the same resistance training program. Maximal strength was assessed at baseline, mid-point (8 weeks) and post-training (16 weeks) for the bench press and leg press exercises. For the bench press, significant increases were demonstrated within G3 and G5 at 8 weeks and at 16 weeks versus baseline (p<0.05). Additionally, for the bench press, G5 (98.2+/-3.7 kg) was significantly stronger than G1 (92.5+/-3.8 kg) at 16 weeks (p<0.05). For the leg press, significant increases were demonstrated within all groups at 8 weeks and at 16 weeks versus baseline (p<0.05). Additionally, for the leg press, G5 (290.8+/-23.5 kg) was significantly stronger than G1 (251.0+/-15.8 kg) at 8 weeks (p<0.01) and G3 (305.0+/-23.9 kg) and G5 (321.7+/-21.7 kg) were significantly stronger than G1 (276.7+/-10.7 kg) at 16 weeks (p<0.05). The findings of the current study indicate that utilising 3 or 5 min rest intervals between sets may result in significantly greater increases in upper and lower body strength beyond the initial weeks of training versus utilising 1-min rest intervals between sets.