Tailce Kaley Moura Leite

Genomic Ancestry, Self-Reported “Color” and Quantitative Measures of Skin Pigmentation in Brazilian Admixed Siblings

A current concern in genetic epidemiology studies in admixed populations is that population stratification can lead to spurious results. The Brazilian census classifies individuals according to self-reported “color”, but several studies have demonstrated that stratifying according to “color” is not a useful strategy to control for population structure, due to the dissociation between self-reported “color” and genomic ancestry. We report the results of a study in a group of Brazilian siblings in which we measured skin pigmentation using a reflectometer, and estimated genomic ancestry using 21 Ancestry Informative Markers (AIMs). Self-reported “color”, according to the Brazilian census, was also available for each participant. This made it possible to evaluate the relationship between self-reported “color” and skin pigmentation, self-reported “color” and genomic ancestry, and skin pigmentation and genomic ancestry. We observed that, although there were significant differences between the three “color” groups in genomic ancestry and skin pigmentation, there was considerable dispersion within each group and substantial overlap between groups. We also saw that there was no good agreement between the “color” categories reported by each member of the sibling pair: 30 out of 86 sibling pairs reported different “color”, and in some cases, the sibling reporting the darker “color” category had lighter skin pigmentation. Socioeconomic status was significantly associated with self-reported “color” and genomic ancestry in this sample. This and other studies show that subjective classifications based on self-reported “color”, such as the one that is used in the Brazilian census, are inadequate to describe the population structure present in recently admixed populations. Finally, we observed that one of the AIMs included in the panel (rs1426654), which is located in the known pigmentation gene SLC24A5, was strongly associated with skin pigmentation in this sample.

EFFECTS OF 24 WEEKS OF PROGRESSIVE RESISTANCE TRAINING ON KNEE EXTENSORS PEAK TORQUE AND FAT-FREE MASS IN OLDER WOMEN

Rabelo, HT, Bezerra, LA, Terra, DF, Lima, RM, Silva, MAF, Leite, TK, and de Oliveira, RJ. Effects of 24 weeks of progressive resistance training on knee extensors peak torque and fat-free mass in older women. J Strength Cond Res 25(8): 2298-2303, 2011—This study examined the effects of resistance training (RT) on knee extensor peak torque (KEPT) and fat-free mass (FFM) in older women. Seventy-eight volunteers (67.1 ± 5.9 years old) underwent 24 weeks of progressive RT (RTG) while 76 (67.4 ± 5.9 years old) were studied as controls (CG). Dominant knee extension peak torque was assessed using an isokinetic dynamometer (Biodex System 3) and FFM measurements were performed by dual-energy x-ray absorptiometry. Muscle strength and FFM were evaluated before and after the intervention in all volunteers. Participants in the RTG trained major muscle groups 3 times per week during 24 weeks. Training load was kept at 60% of 1 repetition maximum in the first 4 weeks, 70% in the following 4 weeks, and 80% in the remaining 16 weeks, with repetitions, respectively, decreasing from 12, 10, and 8. A Split-plot analysis of variance was performed to examine between- and within-group differences, and the level of significance was accepted at p ≤ 0.05. It was observed that the RTG showed significant increases in KEPT (from 89.9 ± 21.8 to 102.8 ± 22.6 N·m; p < 0.05) and FFM (from 36.4 ± 4.0 to 37.1 ± 4.2 kg, p < 0.05). Appendicular FFM was also significantly increased after the intervention period in the RTG (13.9 ± 1.8 to 14.2 ± 1.9 kg, p < 0.05). None of these changes were observed for the CG. Consistent with the literature, it is concluded that a progressive RT program promotes not only increases in muscle strength, as evaluated by an isokinetic dynamometer, but also in FFM as evaluated by the DXA, in elderly women.

Efeitos de 24 semanas de treinamento resistido sobre índices da aptidão aeróbia de mulheres idosas

INTRODUCAO E OBJETIVO: O consumo de oxigenio pico (VO2pico) e o limiar anaerobio (LA) sao amplamente aceitos como importantes medidas da aptidao aerobia. Tradicionalmente, o treinamento aerobio e visto como o principal meio de se aumentar esses indices. Em contrapartida, o treinamento resistido (TR) nao e tipicamente prescrito para este fim. Em individuos idosos, tem sido sugerido que o TR e capaz de aprimorar a capacidade aerobia; entretanto, a tematica e controversa. O objetivo do presente estudo foi verificar os efeitos do treinamento resistido sobre indices da capacidade aerobia de mulheres idosas. METODOLOGIA: Participaram voluntariamente 50 idosas, as quais foram distribuidas em dois possiveis grupos: grupo controle (GC - n = 25; idade media 68,00 ± 6,38) e grupo treinamento (GT - n = 25; idade media 68,04 ± 6,78 anos). Todas as participantes realizaram teste ergoespirometrico em esteira conduzido ate a exaustao voluntaria antes e apos a intervencao. O GT foi submetido a um programa de TR para os principais grupos musculares tres vezes por semana durante um periodo de 24 semanas. Ao GC foi solicitado que mantivessem suas rotinas habituais. Split plot Anova foi utilizada para verificar possiveis diferencas intra e intergrupos. RESULTADOS: Foi observado que o GT apresentou aumento significativo nas variaveis tempo de teste e VO2, tanto no momento do LA como no momento da exaustao. No GC nenhuma das variaveis dependentes sofreu alteracao significativa. CONCLUSAO: Conclui-se que 24 semanas de TR e capaz de promover melhora no desempenho durante teste de esforco cardiopulmonar em uma amostra de mulheres idosas. Futuros estudos serao importantes para elucidar os mecanismos responsaveis por tais adaptacoes.

Lack of association of the ACE genotype with the muscle strength response to resistance training

Abstract Introduction: Previous studies have attempted to link the insertion/deletion (I/D) polymorphism in the angiotensin-converting enzyme (ACE) gene with the variability in muscle strength responses to resistance training (RT); however, the literature is inconclusive. The purpose of the present study was to investigate the association between the ACE I/D genotype and muscle strength response to a RT program in young men. Methods: 124 men (22±2.6 years; 174.8±6.5cm; 71.5±13.8 kg) without resistance training experience were tested before and after 11 weeks of five whole-body RT exercises (bench press, seated row, knee extension, knee flexion and sit ups). The bench press 1RM test was used to assess upper-body muscle strength and the isokinetic knee extensor peak torque (PT) was used as a measure of lower-body strength. Results: At baseline, there were no differences among ACE genotype for 1RM load (54±11.7 kg for II, 58.5±8.9 kg for ID and 52.3±12.2 kg for DD) or knee extensor peak torque (PT) (220.1±36.8 N·m for II, 209.4 ±44.4 N·m for ID and 199.7±32.4 N·m for DD). Moreover, ACE genotype was not associated with lower-body (7.1±10.5%, 15.7±10.4% and 14.1±22.7% for II, ID and DD, respectively) or upper-body strength gains (16.2±8.9%, 14.5±11.3% and 21.9±17.1% for II, ID and DD, respectively) in response to RT. Conclusion: The ACE I/D genotype was not associated with the muscle strength responses to RT.