As an example, the user can ride a stationary exercise bicycle for {HEAD ~ a duration} of {TAIL ~ time}, such as 15 minutes 
As an example , the user can ride a stationary exercise bicycle for { HEAD ~ a duration } of { TAIL ~ time } , such as 15 minutes
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH