Hammerhead sharks are consummate predators that use their oddly shaped heads to improve their ability to find prey.
Their wide-set eyes give them a better visual range than most other sharks. And by spreading their highly specialized sensory organs over their wide, mallet-shaped head, they can more thoroughly scan the ocean for food.
One group of sensory organs is the ampullae of Lorenzini, which allows sharks to detect, among other things, the electrical fields created by prey animals. The hammerhead's increased ampullae sensitivity allows it to find its favorite meal, stingrays, which usually bury themselves under the sand.
The great hammerhead is the largest of the nine identified species of this shark. It can grow up to 20 feet in length and weigh up to 1,000 pounds, although smaller sizes are more common.
Found in temperate and tropical waters worldwide, far offshore and near shorelines, hammerheads are often seen in mass summer migrations seeking cooler water. They are gray-brown to olive-green on top with off-white undersides, and they have heavily serrated, triangular teeth. Their extra-tall, pointed dorsal fins are easily identifiable.
Most hammerhead species are fairly small and are considered harmless to humans. However, the great hammerhead's enormous size and fierceness make it potentially dangerous, though few attacks have been recorded.
The purpose of this study was to investigate the effects of Nordic walking on body composition, muscle strength, and lipid profile in elderly women.
Sixty-seven women were assigned to the Nordic walking group (n = 21), the normal walking group (n = 21), and the control group (n = 25). Nordic walking and normal walking were performed three times a week for 12 weeks. Body weight, body mass index, total body water, skeletal muscle mass, percent body fat, grip strength, sit to stand, arm curl, total cholesterol, triglyceride, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol were measured before and after the program. A Chi-square test, one way analysis of variance, paired t test and repeated-measure two-factor analysis were used with the SAS program for data analysis.
There was a significant difference in the weight (F=8.07, p<.001), grip strength (F=10.30, p<.001), sit to stand (F=16.84, p<.001), arm curl (F=41.16, p<.001), and total cholesterol (F=5.14, p=.009) measurements between the groups. In addition, arm curl was significantly increased in the Nordic walking group compared to the normal walking group and the control group.
The results indicate that Nordic walking was more effective than normal walking in improving upper extremity strength.