Social support is a most powerful expression of human beings. It can make humans overcome barriers that seem impossible. Research shows that athletes, who are supported through being cheered on during events, perform better. However, up until recently, little could be done to cheer athletes during races unless supporters were physically present at the event. We investigate ways in which remote online spectators can support athletes in real-time. Is the support from remote spectators effective? How can we design systems for real-time support and what factors influence their effectiveness? To research this, we iteratively design online crowd interfaces, mobile applications, and devices that allow athletes to communicate with distributed spectators during sport activities. Athletes are able to broadcast their live performance to spectators through locative and biometric data sharing. Concurrently, remote spectators support the athletes by clicking a cheer button that instantly makes the athletes aware that a crowd is following their performance. We then conduct a series of investigations during multiple sport events, using different support modalities and diverse crowds. Results indicate that remote crowd support does motivate the athletes by making the athletes aware that they are being supported. More interestingly, if we categorise supporters into close relatives, acquaintances and unknown spectators, the most effective support seems to be that of acquaintances. This work also provides design guidelines for researchers and designers of remote crowd support systems.