A Bad Day on the Slopes:
A Case Study in Homeostasis and Injury
Joanne is a 45 year old woman who has been an avid skier most of her life. Joanne was excited at the prospect of skiing Diamond Jim, the only black diamond slope that was open today at Massanutten ski resort. The resort had made snow all night and Joanne relished the idea of being one of the first to make tracks. The morning was not too cold (28 F) and sunny as she took the first of two ski lifts needed to get to the peak. She chatted with the few other skiers that were up that early in the morning and was not surprised to see that they all went down the “easy” slope after getting off the first lift.
“More fresh snow for me!” she thought as she pushed off toward the second ski lift and the long ride to the top of Diamond Jim. The snow in this lower area sounded a bit crunchy due to the warming trend from the day before. She kept her eyes open for possible ice patches that she knew often formed after the thawing and freezing of artificial snow. As she reached the second lift, clouds began to cover up the previously clear sky. Joanne began to wonder if she should have worn her thermal underwear, but felt pretty confident that her ski suit and jacket would be enough. She was glad that she brought her bright red wool ski hat as the wind began to pick up on her trip to the top. In anticipation of the first run, Joanne’s mouth was dry and her heart rate and breathing rate were increased.
At the top of the lift, Joanne pushed off and made her first run of the day over the fresh snow. Since she had the slope to herself, she decided to make a really fast run and soon found herself working hard to make the cuts needed to stay on the trail. Her thigh muscles began to experience a burning sensation as she continued to rip her way down the slope. Due to the exertion, she began to sweat a bit and completely forgot about the cold. At the end of the first run, Joanne was so exhilarated that she immediately returned to the lift for a second run.
The second ride to the top seemed very long and the warmth from the first run was fading fast as the clouds and wind increased even more. As she passed over part of the Diamond Jim run, Joanne was disappointed to see that the snow blowers were being turned back on because that could disrupt her vision on the way down. At the top of the lift, the wind was blowing so hard that it was whipping the newly made snow into a near-white out and the temperature had dropped to about 20oF with the wind chill in the teens. Due to the near white-out, the upper lift operator did not notice Joanne get off the lift and turn toward the lip of Diamond Jim. Joanne started down the slope, made the first turn and then ran into the blowing snow from the snow machines. She lost her equilibrium due to the white out and tried to stop. Her left ski tip stuck in a small snow bank as her right ski continued downhill, causing Joanne to twist her left knee until she heard a small pop. Joanne cart wheeled across the snow losing her hat, her skis and both of her poles and then she landed hard on her right shoulder as she heard another loud pop. She blacked out for a few minutes then awoke to find her left knee and right shoulder in serious pain, her head hurting, and her body getting cold. Soon she was shivering uncontrollably. And no one knew she was alone on the slope!
1. Recall that Joanne’s heart and respiratory rate were increased, and that her mouth was dry before she started her run. Explain what was happening to her autonomic nervous system (including which division is the most active) and trace the pathway of the ANS controls that were creating the symptoms noted. What changes do you think were occurring in her digestive and urinary systems at this time?
2. Consider the action of skiing from the perspective of the hip and knee joints. Analyze those actions and create a table that shows what muscles, under control of what nerves, pull on what bones to cause each action. Be sure to include the isometric, isotonic concentric and isotonic eccentric actions as needed. The first column for your table must be the action. This column should describe what is occurring in both English and anatomical terminology (see chapter 9). But only include those actions needed for skiing and group the muscles together by action, with the prime mover listed first. Points will be deducted for unneeded actions. See example below*.
3. Now, pick one of those muscles and trace its control from the appropriate brain structure all the way to the NMJ. Be sure to include all intermediate structures, synapses, plexuses and nerves.
4. Recall that during the first run, Joanne’s thigh muscles were burning. Explain the level of muscle activity involved, and note what metabolic process was providing most to the energy for Joanne’s muscles at that time. What energy molecule is she consuming at this time and what caused her muscles to feel like they were burning? What might Joanne have done the night before to increase her endurance today?