Chapter+26

page 261. 1a) the more menstrual cycles, the higher the bone mineral density; significant increase in bone density once the number of cycles surpasses 10; effect on bone density is not uniform across the bone;

1b) as few as 1-3 has clear effect on entire bone but 4-10 has a different effect depending on the part of the bone/as few as 1-3 has clear effect on entire bone but 4-10 has a different effect depending on the part of the bone; neck of femur has lower density when number is between 4 to 10; trochanter has higher density when number is between 11-13; lowest density reached in neck/ highest density reached in trochanter; both show the relationship that the more menstrual cycles, the higher the bone mineral density.

2 a) may have better diets; may have more moderate running regimes; b) lower bone density might be caused by insufficient nutrient intake; lower bone density might be caused by low estrogen levels; older runners might be over-represented in this category; high energy consumption might forestall bone maintenance;

3a) preserving resources for demanding exercise regime; reduced estrogen impacts uterine and ovarian hormone cycles; b) reduced appetite/ exercise regime is part of weight loss strategy;

page 265 1a) (within a group) higher in winter than summer; summer count in Finnish men (nearly) equal to winter count in Danish men; no change in % normal sperm occurs with the change in seasons; 2a) younger men without pregnant partners have fewer defective sperm; younger men have a lower sperm count; less variability in younger men between the two national groups;

3. Hypothesis supported by sperm count data;