Cross Training Poll for USMS Magazine

This is really worrisome. Do you happen to know if using a Bowflex rather than actual weights, would count as "weight bearing" exercise? I am not a medical professional, nor even a medical librarian, but I thought this was an interesting question and did some quick searches. The only answer I could find specifically regarding Bowflex is from a June 2002 issue of Shape Magazine (so not scholarly, but the answers are from experts, with affiliations given - and obviously not very recent) - here's the relevant passage: Q: Will home-gym equipment such as Bowflex help prevent osteoporosis as well as using free weights or gym machines does? A: It is not the type of equipment that will determine whether a workout ultimately has the necessary bone-strengthening benefits, but rather the angle of the exercises you perform and the amount of resistance you work against. To achieve significant increases in bone mineral density at the hip and spine — where fractures most frequently occur later in life — you need to supplement machine exercises with squats, preferably performed with free weights, says Victoria Jaque, Ph.D., director of the clinical exercise physiology lab at the University of Southern California. Some home machines such as Bowflex allow you to perform squats against resistance, but the bone-density benefits of this type of equipment have not been tested. Leg presses, which you can perform on home or gym weight machines, work the same muscle groups (the thighs and buttocks) as squats do, but since they are performed in a seated or reclining position, they do not place enough stress on the hip or spine — where it's needed most — to improve bone health. “We often have women in our resistance-training studies perform squats to better load the hip,” Jaque says. “We also suggest this in combination with impact activities such as jumping.” Jaque recommends supplementing your strength workout with a set of 50 jumps two or three times a week. Jumping up and down will provide stress at the hip. (A 1998 British study published in the Journal of Bone Mineral Research found that jumping 50 times six days a week for five months increased bone density in the femur by 2.8 percent for premenopausal women. However, postmenopausal women did not benefit from jumping.) When you perform squats and other strength exercises, be sure to use enough weight that your muscles fatigue at no more than eight repetitions. If you use less resistance, you are not likely to gain significant bone mineral density. Even if you perform eight repetitions to fatigue, it typically takes women nine to 12 months of consistent training to increase their bone mineral density by 1.5 percent. Some researchers recommend lifting even heavier weights periodically. “You need to be down in the three- to five-repetition range once a week or once every 10 days,” says William Kraemer, Ph.D., a kinesiology professor at the University of Connecticut in Storrs. Kraemer's recent research, not yet published, suggests that by alternating these heavy workouts with more moderate and light lifting sessions, women ages 20–35 can achieve bone-mineral-density gains of 3 percent over six to 12 months. The 8-minute WORKOUT. (2002). Shape, 21(11), 110. If you expand the search to a more general resistance training, which is what I am guessing Bowflex would be categorized as, you find a lot more stuff. It seems like the earlier women start doing this, the better, and that generally men have a better increase in BMD from such exercise - in fact at least one review article (Martyn-St James, M., & Carroll, S. (2006). Progressive High-Intensity Resistance Training and Bone Mineral Density Changes Among Premenopausal Women: Evidence of Discordant Site-Specific Skeletal Effects. Sports Medicine, 36(8), 683-704.) cites conflicting evidence regarding the benefits for women. :dunno:

This is really worrisome. Do you happen to know if using a Bowflex rather than actual weights, would count as "weight bearing" exercise? I am not a medical professional, nor even a medical librarian, but I thought this was an interesting question and did some quick searches. The only answer I could find specifically regarding Bowflex is from a June 2002 issue of Shape Magazine (so not scholarly, but the answers are from experts, with affiliations given - and obviously not very recent) - here's the relevant passage: Q: Will home-gym equipment such as Bowflex help prevent osteoporosis as well as using free weights or gym machines does? A: It is not the type of equipment that will determine whether a workout ultimately has the necessary bone-strengthening benefits, but rather the angle of the exercises you perform and the amount of resistance you work against. To achieve significant increases in bone mineral density at the hip and spine — where fractures most frequently occur later in life — you need to supplement machine exercises with squats, preferably performed with free weights, says Victoria Jaque, Ph.D., director of the clinical exercise physiology lab at the University of Southern California. Some home machines such as Bowflex allow you to perform squats against resistance, but the bone-density benefits of this type of equipment have not been tested. Leg presses, which you can perform on home or gym weight machines, work the same muscle groups (the thighs and buttocks) as squats do, but since they are performed in a seated or reclining position, they do not place enough stress on the hip or spine — where it's needed most — to improve bone health. “We often have women in our resistance-training studies perform squats to better load the hip,” Jaque says. “We also suggest this in combination with impact activities such as jumping.” Jaque recommends supplementing your strength workout with a set of 50 jumps two or three times a week. Jumping up and down will provide stress at the hip. (A 1998 British study published in the Journal of Bone Mineral Research found that jumping 50 times six days a week for five months increased bone density in the femur by 2.8 percent for premenopausal women. However, postmenopausal women did not benefit from jumping.) When you perform squats and other strength exercises, be sure to use enough weight that your muscles fatigue at no more than eight repetitions. If you use less resistance, you are not likely to gain significant bone mineral density. Even if you perform eight repetitions to fatigue, it typically takes women nine to 12 months of consistent training to increase their bone mineral density by 1.5 percent. Some researchers recommend lifting even heavier weights periodically. “You need to be down in the three- to five-repetition range once a week or once every 10 days,” says William Kraemer, Ph.D., a kinesiology professor at the University of Connecticut in Storrs. Kraemer's recent research, not yet published, suggests that by alternating these heavy workouts with more moderate and light lifting sessions, women ages 20–35 can achieve bone-mineral-density gains of 3 percent over six to 12 months. The 8-minute WORKOUT. (2002). Shape, 21(11), 110. If you expand the search to a more general resistance training, which is what I am guessing Bowflex would be categorized as, you find a lot more stuff. It seems like the earlier women start doing this, the better, and that generally men have a better increase in BMD from such exercise - in fact at least one review article (Martyn-St James, M., & Carroll, S. (2006). Progressive High-Intensity Resistance Training and Bone Mineral Density Changes Among Premenopausal Women: Evidence of Discordant Site-Specific Skeletal Effects. Sports Medicine, 36(8), 683-704.) cites conflicting evidence regarding the benefits for women. :dunno: