Sentence 1: Robbie was competing in a cross country meet. 
 Sentence 3: Robbie wasn't sure he could go on 
 Sentence 4:  He stopped for a minute and stretched his bad leg 
 Sentence 5:  Robbie began to run again and finished the race in second place 
 Option 1: He was halfway through when his leg cramped up. 
 Option 2: He was halfway through when he felt a burst of energy.