The purpose of this study was to compare the effects of short-term exercise training on insulin-responsive glucose transporter (GLUT-4) concentration and insulin sensitivity in young and older individuals. Young and older women [22.4 +/- 0.8 (SE) yr, n = 9; and 60.9 +/- 1. 0 yr, n = 10] and men (20.9 +/- 0.9, n = 9; 56.5 +/- 1.9 yr, n = 8), respectively, were studied before and after 7 consecutive days of exercise training (1 h/day, approximately 75% maximal oxygen uptake). The older groups had more adipose tissue, increased central adiposity, and a lower maximal oxygen uptake. Despite these differences, increases in whole body insulin action (insulin sensitivity index, determined with an intravenous glucose tolerance test and minimal-model analysis) with training were similar regardless of age, in both the women and men (mean increase of 2.2 +/- 0.3-fold). This was accompanied by similar relative increases in muscle (vastus lateralis) GLUT-4 protein concentration, irrespective of age (mean increase of 3.1 +/- 0.7-fold). Body mass did not change with training in any of the groups. These data suggest that older human skeletal muscle retains the ability to rapidly increase muscle GLUT-4 and improve insulin action with endurance training.

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Our students are naturally curious, with powerful intrinsic motives to understand their world. Accordingly, we, as teachers, must capitalize on this inherently active and curious nature so that learning becomes a lifelong activity where students take initiative for learning, are skilled in learning, and want to learn new things. Achieving this goal requires an understanding of student attitudes, beliefs, characteristics, and motivations. To achieve this goal, we administered the intrinsic motivation inventory (IMI) to assess our students' interest and enjoyment, perceived choice, and perceived competence while taking our undergraduate exercise physiology class (46 students; 20 female students and 26 male students). The interest and enjoyment subscale is considered the self-reported measure of intrinsic motivation. The perceived choice and perceived competence concepts are theorized to be positive predictors of both self-reported and behavioral measures of intrinsic motivation. Our results documented a significant increase in course grade with an increase in survey score for the interest and enjoyment subscale of the IMI when female and male students were combined. Specifically, each increase in survey score for the interest and enjoyment subscale of the IMI was associated with a significant (P < 0.05) increase of 3.9% in course grade. However, the increase in survey score was associated with a significantly greater (P < 0.05) increase in course grade for male (6.1%) compared with female (0.3%) students. These results have implications for both classroom practice and educational reform policies.

The "conventional wisdom" is that grades are related to class attendance, i.e., students who attend classes more frequently obtain better grades and class attendance dramatically contributes to enhanced learning. However, the influence of sex (female vs. male) on this relationship is understudied. Furthermore, there have been several studies examining the impact of attendance on course grades that challenge the conventional wisdom. To address these issues, we determined the effect of class attendance on examination scores for female and male students enrolled in our undergraduate exercise physiology class of 51 students (20 female students and 31 male students). The experiment was designed not to interfere with the normal conduct of the course. Attendance was recorded in each class, and, although regular attendance was encouraged, it was not required and did not factor into the final grades. The final grade reflected the average days of attendance for female students only. Specifically, female students earning a grade above the class average attended 89 ± 4% of the classes; however, female students earning a grade below the class average attended only 64 ± 6% of the classes. In sharp contrast, there was no difference in the number of classes attended for male students earning grades above or below the class average (84 ± 3% vs. 79 ± 5%). Accordingly, some male students were absent frequently but scored above the class average, whereas other male students attended many classes but scored below the class average. Thus, the influence of regular attendance on examination performance is more important for female students than male students.

The luteal phase of the female menstrual cycle is associated with both 1) elevated serum progesterone (P4) and estradiol (E2), and 2) reduced insulin sensitivity. Recently, we demonstrated a link between skeletal muscle mitochondrial H(2)O(2) emission (mE(H2O2)) and insulin resistance. To determine whether serum levels of P4 and/or E(2) are related to mitochondrial function, mE(H2O2) and respiratory O(2) flux (Jo(2)) were measured in permeabilized myofibers from insulin-sensitive (IS, n = 24) and -resistant (IR, n = 8) nonmenopausal women (IR = HOMA-IR > 3.6). Succinate-supported mE(H2O2) was more than 50% greater in the IR vs. IS women (P < 0.05). Interestingly, serum P4 correlated positively with succinate-supported mE(H2O2) (r = 0. 53, P < 0.01). To determine whether P4 or E2 directly affect mitochondrial function, saponin-permeabilized vastus lateralis myofibers biopsied from five nonmenopausal women in the early follicular phase were incubated in P4 (60 nM), E2 (1.4 nM), or both. P4 alone inhibited state 3 Jo(2), supported by multisubstrate combination (P < 0.01). However, E2 alone or in combination with P4 had no effect on Jo(2). In contrast, during state 4 respiration, supported by succinate and glycerophosphate, mE(H2O2) was increased with P4 alone or in combination with E2 (P < 0.01). The results suggest that 1) P4 increases mE(H2O2) with or without E2; 2) P4 alone inhibits Jo(2) but not when E2 is present; and 3) P4 is related to the mE(H2O2) previously linked to skeletal muscle insulin resistance.