Krista Austin - Academia.edu (original) (raw)

Papers by Krista Austin

Medicine and Science in Sports and Exercise, 2004

To determine the effect of weight training on measures of iron status in young males and females.... more To determine the effect of weight training on measures of iron status in young males and females. Methods: Forty (27 female, 13 male) non-weight-trained college age subjects participated in a 12-wk weight-training program conducted 3 d·wk Ϫ1 . Blood samples and food diaries were obtained pretraining and at 4-wk intervals. Blood was analyzed for hemoglobin, hematocrit, serum iron (SI), total iron binding capacity (TIBC), transferrin saturation (TS), serum ferritin (SF), soluble transferrin receptor (sTfR), and creatine kinase (CK). Subjects were grouped by SF level (FL, females Յ 20 g·L Ϫ1 ; FN, females Ͼ 20 g·L Ϫ1 ; ML, males Յ 45 g·L Ϫ1 ; MN, males Ն 50 g·L Ϫ1 ) to determine the impact of initial iron status on measured responses. Results: Weight training increased strength and fat-free mass and decreased levels of percent body fat. Hemoglobin concentration declined after 12 wk of training (13.7 Ϯ 1.6 vs 13.2 Ϯ 1.7 g·dL Ϫ1 ), independent of gender or initial iron status. Only the MN group experienced a decline in SF level after 8 wk of training (129.7 Ϯ 77.9 vs 102.0 Ϯ 57.8 g·L Ϫ1 ). No significant changes were observed for hematocrit, SI, TIBC, TS, sTfR, or CK measures. Total iron intake, but not heme or bioavailable iron intakes, declined at the 12th week of training compared with baseline (13.4 Ϯ 6.5 vs 10.7 Ϯ 4.8 mg·d Ϫ1 ) and was not significantly correlated with hematological or iron status measures. Conclusions: Hemoglobin concentration declines without alterations in SI, TIBC, TS, or sTfR after 12 wk of weight training. The SF level of males with adequate iron status is lowered with weight training but not among females or males with low iron status.

Medicine and Science in Sports and Exercise, 2006

To determine if timing of a supplement would have an effect on muscle damage, function and soreness.

Medicine and Science in Sports and Exercise, 2010

enzyme (ACE) and the >-actinin-3 (ACTN3) genes are two of the most studied ''performance genes'' ... more enzyme (ACE) and the >-actinin-3 (ACTN3) genes are two of the most studied ''performance genes'' and both have been associated with sprint/power phenotypes and elite performance. Purpose: To investigate the association between the ACE and the ACTN3 genotypes and sprint athlete status in elite Jamaican and US African American sprinters. Methods: The ACTN3 R577X and the ACE I/D and A22982G (rs4363) genotype distributions of elite Jamaican (J-A; N = 116) and US sprinters (US-A; N = 114) were compared with controls from the Jamaican (J-C; N = 311) and US African American (US-C; N = 191) populations. Frequency differences between groups were assessed by exact test. Results: For ACTN3, the XX genotype was found to be at very low frequency in both athlete and control cohorts (J-C = 2%, J-A = 3%, US-C = 4%, US-A = 2%). Athletes did not differ from controls in ACTN3 genotype distribution (J, P = 0.87; US, P = 0.58). Similarly, neither US nor Jamaican athletes differed from controls in genotype at ACE I/D (J, P = 0.44; US, P = 0.37). Jamaican athletes did not differ from controls for A22982G genotype (P = 0.28), although US sprinters did (P = 0.029), displaying an excess of heterozygotes relative to controls but no excess of GG homozygotes (US-C = 22%, US-A = 18%). Conclusions: Given that ACTN3 XX genotype is negatively associated with elite sprint athlete status, the underlying low frequency in these populations eliminates the possibility of replicating this association in Jamaican and US African American sprinters. The finding of no excess in ACE DD or GG genotypes in elite sprint athletes relative to controls suggests that ACE genotype is not a determinant of elite sprint athlete status.

Medicine and Science in Sports and Exercise, 2009

The maternal inheritance of mitochondrial DNA (mtDNA) has enabled construction of detailed phylog... more The maternal inheritance of mitochondrial DNA (mtDNA) has enabled construction of detailed phylogenies. Analysis of key polymorphisms from these phylogenies allows mtDNA to be assigned to haplogroups, which have been associated with elite endurance performance. Purpose: To compare the frequencies of mtDNA haplogroups found in elite Kenyan athletes with those in the general Kenyan population. Methods: DNA samples were obtained from 221 national level Kenyan athletes (N), 70 international Kenyan athletes (I), and 85 members of the general Kenyan population (C). mtDNA haplogroups were classified by sequencing 340 bases of hypervariable section (HVS I) and by genotyping known restriction sites. Frequency differences between groups were assessed using exact tests of population differentiation. Results: The haplogroup distribution of national (P = 0.023) and international athletes (P G 0.001) differed significantly from controls, with international athletes showing a greater proportion of L0 haplogroups (C = 15%, N = 18%, I = 30%) and lower proportion of L3* haplogroups (C = 48%, N = 36%, I = 26%). Although a high number of international athletes originated from the Rift Valley province relative to controls (C = 20%, N = 65%, I = 81%), subjects from this province did not differ in haplogroup distribution from other regions (P = 0.23). Nor did Bantu subjects differ from Nilotic (P = 0.12) despite an overrepresentation of Nilotic languages among the athletes. Conclusions: International athletes differed in their mtDNA haplogroup distribution relative to the general Kenyan population. They displayed an excess of L0 haplogroups and a dearth of L3* haplogroups. These findings suggest that mtDNA haplogroups are influential in elite Kenyan distance running, although population stratification cannot be ruled out.

Medicine and Science in Sports and Exercise, 2009

Medicine and Science in Sports and Exercise, 2004

To determine the effect of weight training on measures of iron status in young males and females.... more To determine the effect of weight training on measures of iron status in young males and females. Methods: Forty (27 female, 13 male) non-weight-trained college age subjects participated in a 12-wk weight-training program conducted 3 d·wk Ϫ1 . Blood samples and food diaries were obtained pretraining and at 4-wk intervals. Blood was analyzed for hemoglobin, hematocrit, serum iron (SI), total iron binding capacity (TIBC), transferrin saturation (TS), serum ferritin (SF), soluble transferrin receptor (sTfR), and creatine kinase (CK). Subjects were grouped by SF level (FL, females Յ 20 g·L Ϫ1 ; FN, females Ͼ 20 g·L Ϫ1 ; ML, males Յ 45 g·L Ϫ1 ; MN, males Ն 50 g·L Ϫ1 ) to determine the impact of initial iron status on measured responses. Results: Weight training increased strength and fat-free mass and decreased levels of percent body fat. Hemoglobin concentration declined after 12 wk of training (13.7 Ϯ 1.6 vs 13.2 Ϯ 1.7 g·dL Ϫ1 ), independent of gender or initial iron status. Only the MN group experienced a decline in SF level after 8 wk of training (129.7 Ϯ 77.9 vs 102.0 Ϯ 57.8 g·L Ϫ1 ). No significant changes were observed for hematocrit, SI, TIBC, TS, sTfR, or CK measures. Total iron intake, but not heme or bioavailable iron intakes, declined at the 12th week of training compared with baseline (13.4 Ϯ 6.5 vs 10.7 Ϯ 4.8 mg·d Ϫ1 ) and was not significantly correlated with hematological or iron status measures. Conclusions: Hemoglobin concentration declines without alterations in SI, TIBC, TS, or sTfR after 12 wk of weight training. The SF level of males with adequate iron status is lowered with weight training but not among females or males with low iron status.

Medicine and Science in Sports and Exercise, 2006

To determine if timing of a supplement would have an effect on muscle damage, function and soreness.

Medicine and Science in Sports and Exercise, 2010

enzyme (ACE) and the >-actinin-3 (ACTN3) genes are two of the most studied ''performance genes'' ... more enzyme (ACE) and the >-actinin-3 (ACTN3) genes are two of the most studied ''performance genes'' and both have been associated with sprint/power phenotypes and elite performance. Purpose: To investigate the association between the ACE and the ACTN3 genotypes and sprint athlete status in elite Jamaican and US African American sprinters. Methods: The ACTN3 R577X and the ACE I/D and A22982G (rs4363) genotype distributions of elite Jamaican (J-A; N = 116) and US sprinters (US-A; N = 114) were compared with controls from the Jamaican (J-C; N = 311) and US African American (US-C; N = 191) populations. Frequency differences between groups were assessed by exact test. Results: For ACTN3, the XX genotype was found to be at very low frequency in both athlete and control cohorts (J-C = 2%, J-A = 3%, US-C = 4%, US-A = 2%). Athletes did not differ from controls in ACTN3 genotype distribution (J, P = 0.87; US, P = 0.58). Similarly, neither US nor Jamaican athletes differed from controls in genotype at ACE I/D (J, P = 0.44; US, P = 0.37). Jamaican athletes did not differ from controls for A22982G genotype (P = 0.28), although US sprinters did (P = 0.029), displaying an excess of heterozygotes relative to controls but no excess of GG homozygotes (US-C = 22%, US-A = 18%). Conclusions: Given that ACTN3 XX genotype is negatively associated with elite sprint athlete status, the underlying low frequency in these populations eliminates the possibility of replicating this association in Jamaican and US African American sprinters. The finding of no excess in ACE DD or GG genotypes in elite sprint athletes relative to controls suggests that ACE genotype is not a determinant of elite sprint athlete status.

Medicine and Science in Sports and Exercise, 2009

The maternal inheritance of mitochondrial DNA (mtDNA) has enabled construction of detailed phylog... more The maternal inheritance of mitochondrial DNA (mtDNA) has enabled construction of detailed phylogenies. Analysis of key polymorphisms from these phylogenies allows mtDNA to be assigned to haplogroups, which have been associated with elite endurance performance. Purpose: To compare the frequencies of mtDNA haplogroups found in elite Kenyan athletes with those in the general Kenyan population. Methods: DNA samples were obtained from 221 national level Kenyan athletes (N), 70 international Kenyan athletes (I), and 85 members of the general Kenyan population (C). mtDNA haplogroups were classified by sequencing 340 bases of hypervariable section (HVS I) and by genotyping known restriction sites. Frequency differences between groups were assessed using exact tests of population differentiation. Results: The haplogroup distribution of national (P = 0.023) and international athletes (P G 0.001) differed significantly from controls, with international athletes showing a greater proportion of L0 haplogroups (C = 15%, N = 18%, I = 30%) and lower proportion of L3* haplogroups (C = 48%, N = 36%, I = 26%). Although a high number of international athletes originated from the Rift Valley province relative to controls (C = 20%, N = 65%, I = 81%), subjects from this province did not differ in haplogroup distribution from other regions (P = 0.23). Nor did Bantu subjects differ from Nilotic (P = 0.12) despite an overrepresentation of Nilotic languages among the athletes. Conclusions: International athletes differed in their mtDNA haplogroup distribution relative to the general Kenyan population. They displayed an excess of L0 haplogroups and a dearth of L3* haplogroups. These findings suggest that mtDNA haplogroups are influential in elite Kenyan distance running, although population stratification cannot be ruled out.

Medicine and Science in Sports and Exercise, 2009